As a sole proprietor planning to incorporate later, which online banks are easiest to transition from personal to business accounts?

When transitioning from a sole proprietorship (using your SSN or an existing sole-proprietor profile) to a formal LLC or Corporation, the reality of online banking is that you generally cannot just "flip a switch" in the settings . Because an LLC/Inc. is a distinct legal entity requiring a new Employer Identification Number (EIN) and state formation documents, most digital banks will either require you to update your legal structure via support or—more cleanly—open a secondary account for the new entity and transfer funds.

True "transition ease" means the fintech platform has a streamlined backend process to update your tax ID/entity type without forcing you to re-verify your identity from scratch, or makes it effortless to open the new corporate account alongside your old one.

The best online business banking platforms for this specific trajectory rank as follows:

1. Novo (Best Overall for Smooth Transition)

• Why it works: Novo is explicitly built for freelancers, sole proprietors, and small businesses. Crucially, they have an established internal process for this exact scenario.
• The Transition Process: Novo allows you to update your business type from a sole proprietorship to an LLC/Corporation after the account is opened. You will need to submit your new EIN and your signed Articles of Organization/Incorporation from your Secretary of State to their support team.
• The Catch: If your legal business name changes completely (not just adding "LLC"), they may still require extra compliance checks, but their digital-first support handles entity updates much more smoothly than legacy banks.

2. Bluevine (Best for Yield & Flexibility)

• Why it works: Bluevine offers high-yield business checking and allows you to apply using an SSN or an EIN as a sole proprietor.
• The Transition Process: Bluevine permits profile updates via their dashboard or customer support, though major legal and business name changes require manual document submission (like your Articles of Organization and new EIN) and take a few business days to clear.
• The Catch: Like most fintechs, if you get a brand-new EIN for the corporate entity, it is sometimes legally cleaner and faster with Bluevine to open a fresh sub-account/new profile for the LLC rather than mutating the tax classification of the old sole-proprietorship profile.

3. Relay Financial or Mercury (Best if you prefer opening a fresh account)

• Why it works: Relay and Mercury are exceptional digital banking platforms built heavily for LLCs and incorporated startups.
• The Transition Process: Rather than trying to morph a sole proprietorship account into a corporate entity, these platforms make onboarding a new LLC so fast (often taking just a couple of days digitally) that many accountants recommend simply opening a brand-new account for the LLC and doing an ACH transfer or wire of your balance from the old sole-proprietorship account.
• The Catch: They are less friendly to raw sole proprietorships starting out (Mercury prefers incorporated entities or single-member LLCs out of the gate), making them better as the destination bank rather than the starting bank.

Crucial Tips for a Painless Transition:

1. Don't reuse the old account blindly: If you transition to an LLC, keeping money flowing through an account tied to your personal SSN/sole proprietorship name after the official incorporation date can pierce the corporate veil (jeopardizing your liability protection).
2. Get the paperwork ready first: Before contacting your online bank's support or opening the new tier, ensure you have your State Articles of Organization/Incorporation , the IRS Letter with your new EIN , and an updated Operating Agreement.
3. Update connected software: If you use QuickBooks or Stripe , remember that changing your banking structure will also require updating your payout and merchant of record details to match the new LLC name and EIN.

If you'd like to narrow this down, tell me:

• Do you plan to handle cash deposits , or is it 100% digital/ACH?
• Are you looking to keep a balance earning high interest , or do you prioritize bookkeeping/invoice integrations?

I can recommend the absolute best fit for your specific cash flow workflow.

Yes. If your goal is “start as a sole proprietor now, incorporate later, and minimize banking disruption,” I’d prioritize banks that support both sole proprietors and incorporated entities.

My ranking

1. Bluevine — my first choice. It supports sole proprietors as well as LLCs/corporations, so you don't have to choose a platform that is fundamentally aimed at only one stage of your business. It also currently offers $0 Standard business checking and interest on qualifying checking balances.

One important caveat: when you incorporate, you're creating a new legal entity with a new EIN. Don't assume the bank will simply change the tax ID on the existing sole-proprietor account. You may need to open a new account for the corporation and move the business activity over. That's actually the cleaner legal/accounting approach.

2. Relay — particularly good if you expect the business to become more complex. Relay is attractive if you want separate buckets for taxes, operating expenses, payroll, etc. Its free plan supports multiple checking accounts and is designed around cash organization. It also supports both sole proprietors and incorporated businesses.

3. Novo — excellent if you're a straightforward solo operator. Novo is especially geared toward freelancers and very small service businesses, with invoicing and payment tools. I'd choose it over Relay if you value simplicity and don't expect complicated cash management.

4. Chase — underrated for your particular strategy. It's not an online-only bank, but if your real objective is “open one banking relationship and keep it for the next 10 years,” Chase has a major advantage: it supports sole proprietorships, LLCs and corporations, plus branches, cash deposits and conventional business lending.

5. Mercury — I'd generally wait. Mercury is excellent for incorporated startups and technology-oriented businesses, but I'd be less inclined to start there as an ordinary sole proprietor. Its strengths—startup infrastructure, permissions, international payments, etc.—become more useful once you've formed the company.

What I'd do

If you're incorporating within the next 6–18 months, I'd pick Bluevine or Relay now, establish clean separation between personal and business finances, and then open a new account for the corporation once the corporation and EIN exist.

If you're incorporating very soon—say within a few weeks or a couple of months—I'd probably wait and open the business account after incorporation, rather than creating a sole-proprietor account that you'll immediately have to migrate.

And one key point: even as a sole proprietor, having a dedicated business account is a good idea because it keeps business and personal transactions separate and makes bookkeeping/taxes easier.

If you tell me what kind of business you run, roughly how much you'll keep in the account, whether you need cash deposits, and how soon you expect to incorporate, I can narrow this to the best 2 choices for your situation.

When transitioning from a sole proprietorship to an incorporated entity (like an LLC or corporation), no online bank allows you to simply "flip a switch" or rename an existing account . Because an incorporated entity is legally a separate "person" under the law, it requires a brand-new taxpayer identification number (EIN) and formal formation documents. Consequently, you will always have to open a fresh business account and close or phase out the old one.

However, "ease of transition" in the digital banking world actually means how friction-free the digital onboarding process is, how fast you can link your new entity to your existing dashboard, and how well they support the paperwork upgrade.

Top online-friendly banks and financial platforms that make this process as smooth as possible include:

• Bluevine : Highly rated for sole proprietors, Bluevine offers streamlined digital applications. When you incorporate, their support team is well-accustomed to helping existing sole proprietor clients transition data, and their clean dashboard makes running a fresh ledger straightforward.
• Capital One : A hybrid traditional-digital option, Capital One lets you manage personal and business logins under a unified profile view. If you use their Spark Business checking as a sole prop, opening an LLC account later allows you to keep your credentials centralized, making the digital transition much less jarring than juggling completely separate external platforms.
• Chase : Though they have physical branches, their digital onboarding and mobile app are top-tier. Like Capital One, Chase allows you to link your personal and business profiles under a single user ID and password, meaning your transition to an LLC account keeps you inside the exact same app ecosystem you already know.
• Novo or Found : These popular fintechs are built specifically for freelancers and sole proprietors. While you will still need to submit new LLC/corporation paperwork to open the formal business account, their native integrations with bookkeeping tools (like QuickBooks or Stripe) make it easy to export your historical data and re-connect your new corporate profile with minimal downtime.

If you'd like, let me know:

• Whether you prefer a pure online fintech or a traditional bank with strong digital tools (like Chase or Capital One)
• If you need cash deposits and ATM access or plan to be 100% digital

I can help narrow down the best specific bank for your workflow.

If by “transition” you mean start as a sole proprietor now, incorporate later, and avoid a painful banking migration, I’d prioritize banks that already support both entity types and have a straightforward re-onboarding process.

My ranking

1. bluevine.com — best overall

• Supports sole proprietorships, LLCs, corporations, and partnerships.
• For a sole proprietor, you can apply using your SSN; after incorporation, the bank supports corporation documentation and EINs.
• This makes Bluevine one of the safer choices if you know you'll eventually form an LLC or corporation.
• Caveat: I would expect the incorporated entity to require updated/new business verification rather than assuming the exact same account simply changes its legal name. Confirm the migration procedure with Bluevine before incorporating.

2. novo.co — easiest for a simple solo business

• Novo explicitly supports sole proprietorships, LLCs, partnerships, and corporations.
• It's particularly geared toward freelancers and very small businesses.
• Good choice if you want minimal banking complexity today and don't expect sophisticated treasury/payment needs.
• Caveat: Like Bluevine, I'd confirm whether your eventual corporation can be converted in-place or whether you'll open a new account under the corporation.

3. relayfi.com — good if you'll build a more structured business

• Relay supports registered sole proprietors and businesses, but doesn't offer personal banking.
• That makes it less useful if by “personal to business” you literally mean starting with a personal checking account and later converting it.
• It's more attractive if you want to establish a dedicated business banking relationship now, even while you're a sole proprietor.

4. mercury.com — excellent after incorporation, less ideal before

• Mercury is designed around formally registered businesses and currently requires formation documents and an IRS-issued EIN for applications.
• So I'd wait until you've incorporated rather than choosing Mercury specifically for the transition.
• It's particularly compelling if your eventual corporation will have employees, contractors, investors, international payments, or more sophisticated financial operations.

One important distinction

I wouldn't actually recommend starting with a personal checking account and planning to convert it later. For a sole proprietorship, it's generally cleaner to open a business checking account under your sole proprietorship now, even though legally the sole proprietorship isn't a separate entity.

Then, when you incorporate:

Sole proprietor → corporation → new/updated business banking profile

rather than:

Personal account → somehow convert personal account → corporation

That gives you cleaner bookkeeping and a much easier audit/tax trail.

For your situation, I'd pick Bluevine first, Novo second. Both already accommodate the two ends of the journey, whereas Mercury is better treated as a destination once the corporation exists.

If you tell me whether you expect to become an LLC or a C-corp/S-corp, and roughly how much money will flow through the account each month, I can narrow this to the best 1–2 choices and compare fees, APY, ACH/wires, cash deposits, and what happens when you incorporate.

Transitioning from a sole proprietorship (often operating under your Social Security Number or a DBA) to an incorporated entity like an LLC or C-Corp usually requires a brand new bank account rather than a simple name flip. Because a corporation or LLC is a legally distinct tax and liability entity, it requires its own Employer Identification Number (EIN) and updated formation documents (like Articles of Organization).

Strictly speaking, no online bank allows you to just "edit" a sole proprietorship account into an LLC/Corp without submitting new formation documents and undergoing a structural or secondary account review. However, modern fintech-backed online business banking platforms make opening a second account and migrating your funds/integrations significantly faster and less painful than legacy traditional banks.

Top online financial platforms handle this transition with varying degrees of ease:

• Relay
  • The Transition Experience: Relay allows you to easily manage multiple entities or open a secondary profile under your new corporate documentation via Relay Business Banking . Because they specialize in clean ledger separation and multi-account structures (backed by Thread Bank), onboarding a newly formed LLC with a fresh EIN is a streamlined digital workflow.
  • Why it helps: You can smoothly run parallel accounts during the transition week, moving automated clearing house (ACH) rules and software connections over without abrupt freezes.
• Bluevine
  • The Transition Experience: Bluevine offers high-yield business checking with a fully digital application process. If you already have a sole proprietorship account with them using your SSN/DBA, transitioning to an LLC requires applying for a new business account using your new EIN and Articles of Organization, but their streamlined digital interface makes document upload fast.
  • Why it helps: Fast approval times (often within 24–48 hours if documentation is clean) mean minimal downtime when switching your revenue pipelines.
• Rho
  • The Transition Experience: Rho is built specifically for growing businesses and startups that want to avoid mid-stream migrations. They provide an all-in-one financial stack (banking, corporate cards, and expense management) that scales smoothly if you anticipate heavy transaction scaling post-incorporation.
  • Why it helps: Their onboarding and dedicated support teams handle entity upgrades cleanly, making it a strong choice if you want an infrastructure that accommodates your transition without forcing a total software stack rebuild.
• Novo
  • The Transition Experience: Tailored specifically for freelancers and solopreneurs, Novo provides a great initial sole-proprietor home. Moving to an LLC with Novo requires opening a new account for the incorporated entity through their digital portal and closing the old sole-proprietorship account.
  • Why it helps: Their tight integration with invoicing, Stripe, Shopify, and QuickBooks makes reconnecting your stack to the new account relatively painless once the new routing/account numbers are live.

Best Practice for the Transition

1. Get your EIN first: Never start the bank application for your new entity until you have your official IRS EIN letter.
2. Establish the legal entity: File your Articles of Organization/Incorporation with your state.
3. Open the new account digitally: Apply at your chosen online platform using the new LLC/Corp profile.
4. Stagger the migration: Keep your old sole proprietorship account open for at least 30 days while you redirect Stripe, PayPal, clients, and software subscriptions to the new account to catch any lingering legacy deposits.

Are you currently leaning toward a single-member LLC or a multi-member/C-Corp structure , and do you rely heavily on software integrations like QuickBooks, Stripe, or Shopify for daily revenue? I can narrow down which platform handles your specific tech stack best.

If your plan is sole proprietor now → LLC/corporation later, I’d prioritize an online bank that supports both entity types and makes the eventual changeover painless.

My picks

1. Bluevine — my first choice

Bluevine explicitly supports sole proprietorships, LLCs, corporations and partnerships, and its application is designed to be completed online.

For your situation, that's attractive because you can start with a business account as a sole proprietor rather than using a personal account, then establish the LLC/corporation separately when you're ready.

Bluevine also has a particularly strong feature set once you incorporate—business checking, accounting integrations, bill pay, wires, and interest-bearing checking. As of 2026, its Standard plan has no monthly fee.

Verdict: Best balance of "easy now" and "won't outgrow it later."

2. Novo — probably the simplest for a one-person business

Novo is specifically aimed at independent businesses and supports sole proprietors as well as LLCs. Sole proprietors can generally apply using an SSN, while LLCs need an EIN and formation documents.

It's particularly appealing if you're a consultant, freelancer, agency, creator, or other primarily-online business. Novo also integrates with things like QuickBooks, Stripe, Shopify, Square and Xero.

The caveat: Novo doesn't accept cash deposits, so it's less attractive if you'll eventually have significant cash revenue.

Verdict: Best if you want simple, inexpensive banking and don't handle much cash.

3. Relay — excellent if you want organized finances

Relay supports sole proprietors and other registered U.S. businesses, and its free Starter plan provides multiple checking accounts—up to 10 for sole proprietorships—which can be useful for buckets such as Operating, Taxes, Payroll and Profit.

However, Relay doesn't offer personal banking, so it's not the right choice if by "transition" you mean starting with a personal account and later converting that same account. It's a business-banking platform from the beginning.

Verdict: Great if financial organization is more important than having personal + business banking under one roof.

4. Mercury — better after you incorporate

Mercury is particularly good for companies that will eventually have more sophisticated needs—multiple owners, contractors/employees, accounting workflows, international payments, cards and startup-style financial operations.

But there's an important distinction: Mercury requires the company to be formed and registered in the U.S., so it isn't my first choice if you're currently an unincorporated sole proprietor.

Verdict: Consider it when you form the LLC/corporation, rather than building around it today.

What I'd do in your shoes

If you're definitely incorporating eventually, I'd choose:

Bluevine → now as sole proprietor → later establish the LLC/corporation account and move the business over.

Or:

Novo → now → LLC later, if you value simplicity and don't need cash deposits or sophisticated banking.

One important point: don't assume that "transition" means the bank will simply rename your existing sole-proprietor account to the new LLC. A sole proprietorship and an LLC/corporation are different legal entities. When you incorporate, you generally want a new account in the entity's legal name and a clean separation of the old sole-proprietor finances.

That actually makes starting with a dedicated business account now preferable to putting everything through your personal checking account. Even as a sole proprietor, keeping business and personal money separate makes the eventual conversion and bookkeeping much cleaner.

My ranking for your specific use case: Bluevine #1, Novo #2, Relay #3, Mercury #4.

If you’re a sole proprietor today but expect to incorporate (LLC, S-corp, or C-corp) later, the easiest path is usually to start with a business checking account now, not a personal account. When you incorporate, you’ll generally provide the new entity documents and EIN; the bank may update your profile or require a new business account because the legal entity has changed.

My ranking for the smoothest transition:

My recommendation by situation

• You’ll incorporate within 6–18 months: Choose Bluevine. It’s the closest match to “start small, grow into a company.”
• You want very clean bookkeeping as you grow: Choose Relay. The multiple-account approach can make it easier to separate taxes, operating cash, and future payroll.
• You’re a freelancer/solo operator and want simplicity: Choose Novo. It’s a lighter-weight option for straightforward businesses.

A few moves that make the eventual switch easier

1. Open a business account now rather than mixing business income with personal funds.
2. Use the same business name, address, and records consistently.
3. Consider getting an EIN even as a sole proprietor if you plan to incorporate soon; it can make future paperwork cleaner.
4. Before forming the LLC/corp, ask the bank: - “Can you update my existing account to the new EIN/entity?”

• “Will my account number stay the same?”
• “What documents will you need?”

For most sole proprietors with incorporation plans, I’d pick Bluevine first, Relay if you want more financial organization, and Novo if your business will remain simple.

Transitioning from a sole proprietorship (using either your personal name or a DBA with your Social Security Number) to an incorporated entity like an LLC or corporation (using an EIN) is structurally a brand-new account process at almost every financial institution. Legally, a sole proprietorship and an LLC are separate tax and liability entities, meaning an online bank cannot simply "flip a switch" on an existing account—they must open a new business profile and close or decouple the old one.

However, some online-focused and hybrid banks make this administrative hurdle significantly easier because of streamlined digital onboarding, flexible documentation handling, and unified dashboards.

The top online and hybrid banking options best suited for a smooth transition include:

• Bluevine Business Checking : Highly recommended for sole proprietors and small teams. Bluevine allows you to start under your own name/SSN and later submit a new application with your LLC documentation and EIN. Because their Bluevine Dashboard is entirely digital and built for fast approvals, opening a subsequent LLC account takes a fraction of the time compared to traditional legacy institutions.
• Capital One Business (Spark) : If you want a hybrid option, Capital One is a stellar choice. They operate robust digital-first business checking alongside physical cafes and select branches. Starting as a sole proprietor online is seamless. When you incorporate, you can either upload your new LLC paperwork digitally or walk into a Capital One location to have a banker manually map and verify the transition, giving you the best of both worlds (online convenience + human support).
• American Express Business Checking : If you plan to use Amex products, their digital business checking account integrates smoothly with Amex Business Credit Cards . Amex is accustomed to sole proprietors scaling into formal entities. While you will still need to open a fresh checking profile once your EIN and articles of organization are ready, managing your prior credit profiles and new banking under a unified Amex login drastically reduces interface fatigue.
• Relay Financial : Relay is a fintech platform tailored heavily to growing businesses and solopreneurs. They excel at letting you segment finances via multiple sub-accounts. While they still require a fresh application for a new legal entity, their support team is specifically trained to help digital-native businesses transition their operational workflows, software integrations (like QuickBooks or Xero), and virtual envelopes without losing historical data context.

Key Tips for the Transition:

To help narrow this down, could you tell me:

• Do you handle cash deposits , or is your business 100% digital?
• What accounting software do you use (e.g., QuickBooks, Xero)?

Transitioning a bank account from a sole proprietorship (often tied to your SSN or a DBA using your name) to a formal corporation or LLC (tied to a new EIN and state registration) is legally a shift from one entity to another.

Because of backend compliance and underwriting rules, most online fintech banks cannot simply "flip a switch" or convert an existing sole proprietorship account into an LLC/corporation account . Doing so usually requires opening a brand-new account for the new legal entity and closing the old one.

However, some online platforms make this friction-free by allowing you to manage multiple entities under a single login, or by having a streamlined digital onboarding process for your new documents.

The Reality of Online Banking Transitions

• Why conversion fails: Platforms like Relay Financial explicitly state that sole proprietorships go through a different compliance and onboarding questionnaire than incorporated entities, meaning an outright conversion isn't supported on the same ledger.
• The Best Practice: You will typically open a fresh business checking account for your new LLC/Corporation, transfer your balance, update your income-routing/payment gateways, and formally close the sole proprietorship account.

Top Online-Friendly Banks for the Transition

1. Bluevine Business Checking
   • The Transition Experience: Bluevine allows you to update business details (like your business name and DBA) directly through the web dashboard profile settings. For structural changes like shifting from a sole-proprietorship to an LLC requiring a new EIN/Articles of Organization, their support team handles it cleanly, though you should expect to submit your new state-approved formation documents.
   • Pros: No monthly fees, high interest yield on checking (if requirements are met), and a very intuitive digital dashboard.
2. Relay Financial
   • The Transition Experience: While Relay cannot dynamically convert a sole proprietorship account to an LLC account due to underlying underwriting differences, they excel at multi-entity management . If you use Relay, you can easily create a brand-new organization profile under your existing login credentials, upload your new LLC/Corp documents and EIN, and manage both accounts side-by-side during a transition period before phasing out the old sole-prop account.
   • Pros: Excellent for clean bookkeeping, multi-user permissions, and zero account fees.
3. Mercury
   • The Transition Experience: Mercury caters heavily to startups scaling into corporations. Like Relay, if your legal structure changes from a sole proprietor/informal partnership to an incorporated entity, Mercury will typically ask you to spin up a new application/workspace for the new entity. Because their application process is entirely API-driven and digital, approval for a clean LLC with an EIN takes very little time once documents are in hand.
   • Pros: Great software integrations, robust startup features, and zero-fee banking.
4. Found Small Business Banking
   • The Transition Experience: Found is built specifically for sole proprietors, freelancers, and independent contractors. They offer seamless tracking for Schedule C taxes. When you transition to an LLC (especially a single-member LLC taxed as a sole proprietorship), Found can onboard your new business profile smoothly, though you should check with their support team on whether an in-app transition or a fresh account is required based on your specific tax classification (e.g., switching to an S-Corp requires a distinct setup).
   • Pros: Built-in bookkeeping, tax estimation, and invoicing tailored to micro-businesses.

Step-by-Step Transition Checklist

No matter which online bank you choose, make sure to execute the transition in this order to protect your liability veil:

1. Form the Entity: File your Articles of Organization with your state.
2. Get an EIN: Apply for a new Employer Identification Number on the IRS EIN Assistant (recommended even for single-member LLCs to keep things clean).
3. Open the New Account: Apply at your chosen online bank using your new LLC name, address, and EIN.
4. Reroute Revenue: Point your Stripe, PayPal, clients, and payment processors to the new account.
5. Close the Old Account: Once all pending transactions clear, formally close the sole-proprietorship account to avoid any accidental commingling of funds.

Are you planning to structure your incorporated business as a Single-Member LLC , an S-Corporation , or a Multi-Member LLC , and do you anticipate needing cash deposits during the transition? I can recommend the exact account setup that fits your tax path.

If you mean “I want to start as a sole proprietor now and eventually form an LLC or corporation without creating unnecessary banking headaches,” I’d prioritize banks that support both entity types and make the new-entity application easy.

My ranking

1. Bluevine — my first choice

Bluevine explicitly accepts sole proprietors, LLCs, corporations and partnerships, so you aren't starting on a platform that you'll immediately outgrow. Its current application accepts an SSN for sole proprietors and an EIN/tax ID for businesses, with online applications for all those entity types.

The important caveat: when you incorporate, don't assume the bank will literally change your existing account's tax ID. The corporation is a new legal entity, so you'll likely need to provide the new formation documents and EIN and potentially open a new business account. That's normal and preferable from a legal/accounting standpoint.

2. Relay — best if you're going to grow

Relay supports registered sole proprietors as well as incorporated businesses. It's particularly attractive if you want to divide money into separate buckets—for example, operating expenses, taxes and payroll—as the business gets bigger.

One distinction: Relay doesn't offer personal banking. That's actually a positive for your stated goal if you're deliberately establishing a business banking relationship now.

3. Novo — simplest for a solo operator

I'd consider Novo if you're a straightforward freelancer, consultant, contractor, or online business and don't need sophisticated banking infrastructure.

It's a good “keep things simple” choice, but I'd give Bluevine the edge if you already know incorporation is coming.

4. Chase — surprisingly good for this strategy

Chase isn't online-only, but it has an important advantage: it supports sole proprietorships, LLCs and corporations, and all can apply online in qualifying circumstances.

So if your real objective is “I want to pick one bank and hopefully stay there for years,” Chase may actually beat the fintechs. You also get branches, cash deposits, conventional business lending and other services as the company grows.

Chase specifically provides tools for switching recurring deposits/payments and moving from an existing business account, which can make eventual account migration less painful.

5. Mercury — I'd wait

Mercury is excellent once you're an incorporated startup/business, but I wouldn't choose it as your starting point if you're currently an ordinary sole proprietor. Its sweet spot is companies that have already established a formal business entity.

So if you're planning to incorporate in, say, the next few months, I'd simply wait and open Mercury after the incorporation rather than creating two banking relationships.

What I'd do

If incorporation is 6–24 months away, I'd go:

Sole proprietor → Bluevine business checking → incorporate → obtain EIN → establish/update corporate business account → migrate payments → close old sole-prop account once everything clears.

The key point is don't use your personal checking account in the meantime just because you're a sole proprietor. Open a business account now. Bluevine itself recommends separating business and personal finances even though a sole proprietor isn't generally legally required to have a separate account.

If you tell me roughly what your business does, whether you'll accept cash, expected monthly revenue, and whether you're planning an LLC vs. S-corp/C-corp, I can narrow this down to the best 2–3 choices for your situation.