Here is a conversation we have almost every week with a practice who just onboarded at Accel Health. They signed up with us and as part of the payer enrollment process, we ask for them to upload a voided check. They send a screenshot from their banking app. We tell them it will not work, and that they will need an account at a traditional bank before we can submit.

The usual response is some version of: but my bank is FDIC insured.

They are right. It usually is. That is not the problem, and understanding what the problem actually is will save a practice weeks of avoidable delay.

First, the myth about FDIC insurance

Mercury, Brex, and Found are financial technology companies, not chartered banks. But they all work with FDIC-member banks behind the scenes, and customer deposits are insured on a pass-through basis. In some cases the coverage is well above the standard $250,000, because funds get distributed across a network of partner banks.

• Mercury checking and savings: not a chartered bank, but FDIC insured on a pass-through basis through Choice Financial Group and Column N.A., plus a sweep network
• Brex checking: not a chartered bank, but the account itself is held at Column N.A., Member FDIC
• Found: not a chartered bank, but FDIC insured on a pass-through basis through Lead Bank, Member FDIC
• Mercury Treasury and Brex Treasury: investment accounts rather than checking, and not FDIC insured at all
• Chase, Bank of America, and credit unions: chartered institutions with direct coverage

So if a payer or a Medicare contractor turns your enrollment away, insurance is not the reason they are doing it. There is no CMS rule that bans fintech platforms, and no payer publishes a list of approved banks. The rejection is a documentation problem, and it is a predictable one.

What payers actually require

Enrollment is a documentation exercise. To set up electronic payments, a payer needs to prove that the account belongs to you, the enrolled provider, and to nobody else. Medicare does this through Form CMS-588, and most commercial payers use a near-identical process. The form asks for one of two things:

• An original voided check showing the account name, routing number, account number, and account type, or
• A letter on the bank's own letterhead with the same information, plus a bank officer's name and signature

That is the whole wall. Read it again with a fintech account in mind and the problem becomes obvious.

The four ways a fintech account fails enrollment

These four failures are independent of each other. Any one of them is enough to stop an application.

1. There is no check to void

Fintech accounts are digital-first. Most customers never order checks, and Medicare's checklist specifies that the check must be original, not a copy. A PDF pulled from a banking dashboard does not satisfy it.

2. The letter comes from the wrong company

The confirmation letter you can download comes from the fintech platform, not from the FDIC-member bank actually holding the money. It carries no bank letterhead and no bank officer's signature, which are the two things the form specifically asks for.

3. The account is not in the entity's legal name

The account must bear the legal business name exactly as it is enrolled with the payer and reported to the IRS. Fast online signups often land under a personal name or a DBA instead, and a reviewer comparing the check to the W-9 will catch the difference.

4. The branding suggests a middleman

The routing number belongs to a partner bank the reviewer has never seen you name. To someone trained to spot payments being routed through third parties, that pattern gets flagged on sight.

That last one deserves a note. Medicare regulations prohibit paying anyone other than the enrolled provider, with narrow exceptions for government agencies, court orders, and billing agents. There is no exception written for financial institutions, and the person signing the CMS-588 certifies that they have sole control of the account. A structure where a non-bank company sits between the provider and the bank is not necessarily a violation of any of that, but it looks unfamiliar to a reviewer whose job is to catch exactly that shape.

Why Medicare is not worth gambling on

Some fintech accounts do get through with commercial payers. Reviewers differ, Medicare Administrative Contractors differ, and commercial payers differ from each other and from Medicare. We have seen the same bank clear one payer and get rejected by the next one in the same submission batch.

For Medicare specifically there is no gamble to take. Form CMS-588 accepts an original voided check or an officer-signed bank letter and nothing else, and a fintech platform can produce neither. The enrollment cannot be submitted, not because anyone disapproves of the bank, but because the required document does not exist.

The reason we push customers to switch even for commercial payers is timing. A rejected EFT enrollment does not come back the next day. It comes back weeks later, you open a compliant account, you resubmit, and you re-enter the payer's queue from the beginning. On an enrollment timeline that already runs 60 to 120 days per payer, one avoidable rejection can cost a practice a quarter of revenue it has already earned and cannot collect.

You do not have to give up your fintech account

This is not an argument that Mercury or Brex are bad products. Plenty of our customers keep using them and like them. The fix is to open one traditional business checking account, point your payer enrollments at it, and move funds to your primary platform on whatever schedule you like. The traditional account exists to satisfy the paperwork. It does not have to be where you actually run the business day to day.

What to do before your applications are submitted

1. Open a business checking account at a chartered bank or credit union

Any traditional institution works. A local credit union is fine, and is often faster to deal with than a national bank when you need a branch officer to sign something.

2. Open it in your exact legal entity name

It must match the name on your W-9 and your payer enrollment record character for character. "Valley Primary Care LLC" and "Valley Primary Care, LLC" are not the same thing to a reviewer comparing the two documents.

3. Order paper checks, even if you will never write one

Ask for standard business check stock with your entity name preprinted. Counter checks and starter checks without a printed name will not be accepted.

4. Ask the branch for a bank verification letter

On the bank's letterhead, listing the account name, routing number, account number, and account type, and signed by a bank officer. Ask for two or three originals while you are there, because you will need them again for the next payer.

5. Send both documents to your enrollment team

A voided check and the letter. Having both on file means whichever version a given payer asks for is already available, and nobody has to come back to you mid-application.

How Accel Health handles bank documentation

Accel Health flags banking problems during provider intake, before an application is built, rather than after a payer returns it. When a practice comes to us on a fintech account, we tell them at onboarding what to open and exactly what to ask the branch for, so the compliant account and its documentation are ready before the first submission goes out. Verified banking documents are stored in the provider's file alongside licenses and certifications, so the same voided check and bank letter can be reused across every payer without chasing the practice again. The goal is the same as everywhere else in enrollment: a clean first submission, because a returned application costs weeks that nobody gets back.

See how provider intake and document collection work on the Accel Health credentialing platform.

FAQ

Are Mercury, Brex, and Found FDIC insured?

Their checking products are, on a pass-through basis through partner banks that are FDIC members. None of the three is a chartered bank itself, and their treasury and investment products are not FDIC insured at all. FDIC status is not what causes payer enrollment rejections.

Why does Medicare reject fintech bank accounts?

Medicare does not have a rule naming fintech platforms. Form CMS-588 requires either an original voided check or a letter on bank letterhead signed by a bank officer, with no alternatives. Fintech platforms are not chartered banks, so they cannot produce either document, which makes the enrollment impossible to submit.

What bank documents do I need for payer enrollment?

An original voided check showing your legal business name, routing number, account number, and account type, or a letter on your bank's letterhead with the same information plus a bank officer's name and signature. Keeping both on file covers every payer variation without a follow-up request.

Can I keep using my fintech account for the rest of my business?

Yes. Open a traditional business checking account for payer payments only, and transfer funds to your preferred platform on whatever schedule works for you. The traditional account only has to exist and satisfy the documentation requirement.

What happens if I submit with a fintech account anyway?

The application is likely to be rejected, often weeks after submission. You then have to open a compliant account, resubmit, and re-enter the payer's review queue from the beginning, which can add 30 to 60 days to an enrollment that already runs 60 to 120 days.

Does this apply to commercial payers or only Medicare?

Medicare is the strictest and the most predictable, because CMS-588 allows no alternatives. Most commercial payers use a near-identical process and the same two document options, though reviewers vary. A compliant account satisfies all of them at once, which is why it is worth setting up before applications go out rather than payer by payer.

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