How to Switch Medical Billing Companies Without Revenue Loss

Whether to switch should rest on your own numbers, not on how daunting the move feels. Pull your baseline first: denial rate, days in A/R and aged A/R over 90 days, each with the definition your current vendor uses, because a rate computed on charges and a rate computed on allowed amounts are different numbers. If the same denial reasons repeat, aged A/R keeps growing, or nobody can explain why claims are not getting paid, the vendor may be the cause, but a change in payer mix or in the services you bill can produce the same symptoms. Our denial-rate guide lists the few published figures with their denominators and explains what drives denials by specialty.

Revenue can be lost in four places during a billing transition: claims that fall into a gap between the old company stopping and the new one starting, aged A/R from the previous company that nobody takes ownership of, remittances still routed to the old company's clearinghouse, and front-end processes like eligibility verification and authorization tracking that break down during handoff. Each can be given an owner and a date in writing before cutover, which is what the rest of this guide does.

Not necessarily. A billing company change and a billing software change are separate decisions. Some billing companies work inside the practice's existing practice management (PM) and EHR systems, so the practice's data and clinical workflow stay where they are; if you bill Medicare, the billing-agent record on your enrollment still changes, and so can the clearinghouse and the remittance routing, as the next section shows. Others run billing on their own platform, which can bring better tooling but adds a data conversion, staff retraining and an exit question: who holds the billing data when you leave. Both models are legitimate; the mistake is letting a vendor bundle an unplanned software conversion into what should be a billing-only transition.

If you want new software as well, sequence the changes — stabilize claims processing first, then migrate systems. MedPrecision is EHR-agnostic: it works inside your existing PM/EHR as part of its outsourced medical billing services and can manage a later software migration through EHR and software setup. Request a transition quote to scope your current system before you commit.

CMS calls a billing vendor a billing agency or billing agent. A billing agency does not enroll in Medicare: it submits claims in the name and billing number of the provider that furnished the service (Program Integrity Manual, chapter 10, section 10.6.8). If the new vendor works inside your PM/EHR, the software itself does not have to change; the records below sit outside it and are the ones that can change. The table covers Medicare fee-for-service only. Medicaid, Medicare Advantage and commercial payers each have their own enrollment steps, so work the payer list one payer at a time.

CMS explains that the payment conditions exist so the billing agent has no financial interest in how much is billed or collected (Claims Processing Manual, chapter 1, section 30.2.4). A fee set as a percentage of collections is tied to how much is collected, so on a plain reading a vendor paid that way does not meet the compensation condition; keep the practice as the Medicare payee. Under MedPrecision's terms of service, payer and patient payments deposit directly to the client's own bank account.

Other payers set their own steps. UnitedHealthcare's guide, for example, says a billing service company first enrolls for access to Optum Pay, then associates its Optum Pay account with the practice so it can access the claim payment information needed to post and close claims (UnitedHealthcare Care Provider Administrative Guide, chapter 10, read 1 October 2026).

For form-by-form detail, see the CMS-855B guide and the guide to EFT and ERA enrollment; for claims routing, see clearinghouse versus direct payer submission. The CMS and eCFR text on this page was read on 1 October 2026; the eCFR was current as of 29 September 2026.

Filing and appeal deadlines run from the date of service or from the date you receive the payer's notice, and none of the rules below pauses for a change of billing company. The table lists the ones with a published rule; the Medicare rows are for fee-for-service Medicare, and commercial deadlines sit in each payer contract and any state requirement.

On day one, sort unbilled charges by filing deadline (date of service plus the payer's limit), soonest first: that is where the money closest to expiring sits. Move every appeal date into the practice's own tracker, not the outgoing vendor's worklist. A Medicare claim that has been accepted keeps its permanent receipt date, which is the date used to decide whether it was filed on time (Claims Processing Manual, chapter 1, section 70.3), so a change of vendor does not move it. For the exceptions list and what to do after a CO-29 denial, see the guide to timely filing limits and the CO-29 denial.

There is no fixed duration, because four dates set your calendar. Work backwards from the earliest of them:

1. Your contract's notice period. Read the termination and notice clause first; it sets the earliest date the engagement can end without cause.
2. Medicare notices. Your Medicare contractor must be told in writing in advance of a change of billing agent or clearinghouse, and for a physician practice the billing-agency update on the CMS-855 is due within 90 days.
3. Payer enrollment turnaround. Each payer processes its own EDI, ERA and EFT enrollment on its own timetable, which neither the outgoing nor the new vendor sets.
4. Filing deadlines on unbilled charges. The soonest filing deadline among your unbilled charges sets how soon the new vendor has to be transmitting.

The illustrative plan below lays the same work out over 90 days, with owners and exit gates: access and baseline in days 1-10, enrollment in days 11-20, cutover in days 21-30.

A cutover is a handoff of every open item, not of a single date. Run it in this order:

1. Fix the cutover date in writing. Ask your Medicare contractor in writing whether it can have both agents on file for the overlap. If it can, the outgoing vendor transmits every claim for dates of service up to the cutover date and the new vendor transmits every claim for dates of service after it. If it cannot, set one effective date for the change of agent: everything transmitted after that date, including charges for earlier dates of service that were never billed, goes through the new vendor, and the outgoing vendor hands over its unbilled-charge list before that date. Either way, list the pre-cutover charges still unbilled and name who bills them. Who works the A/R on claims already filed is a separate decision, made in the legacy A/R plan below.
2. Inventory every open item and give each one an owner: unbilled charges, claims awaiting payment, denials and appeals in flight with their deadlines, patient balances and unapplied cash.
3. Move the front end: eligibility verification schedules, active prior authorizations and pending referrals.
4. Tell staff and patients: which vendor handles which claims from the cutover date, and any change to the address or phone number on statements.
5. Send the advance notices before the cutover date, and file the Medicare and payer changes using the table above.
6. Run the overlap as a parallel run, not a double submission. The new vendor processes the same charges and compares its results with what the outgoing vendor sends, and one source transmits each claim.
7. Reconcile weekly for the first 30 days: claims submitted, accepted and rejected; dollars posted against the remittances received; and the oldest open denial. Then audit the first full billing cycle against the day-1 baseline.

What does running in parallel actually mean?

A parallel run means both vendors can see and reconcile the same work. It does not mean both transmit the same claim. Medicare's claims systems auto-deny or reject exact duplicate claims, and for physician claims an exact duplicate matches on beneficiary, provider number, dates of service, type of service, procedure code, place of service and billed amount (Claims Processing Manual, chapter 1, section 120). Some Medicare contractors may not be able to accommodate more than one agent for a provider (chapter 24, section 40.2.2.3).

Ask in writing, and before notice if the contract allows, for the items below.

• Every claim, charge, payment and adjustment with its dates, as machine-readable files rather than a PDF summary
• Open A/R by payer with claim status and the last action taken
• Unbilled and held charges by date of service, with the reason each was held
• Denials and appeals in flight, with the payer deadline and the proof of filing
• Proof of timely filing for claims still inside a filing or appeal window. UnitedHealthcare's 2026 administrative guide, read 1 October 2026, says proof of timely filing must include confirmation that the claim was received and accepted within the filing limit, lists an EDI report and a billing/accounting software statement among the acceptable documents, and says a rejected claim is not proof (UnitedHealthcare Care Provider Administrative Guide)
• Remittance (835) files, patient balances and statement history, and the fee schedules, payer contracts and credentialing records you supplied

The exit paperwork has a legal floor. The business associate agreement must provide that, at termination, the vendor will, if feasible, return or destroy all protected health information it still holds and keep no copies or, if that is not feasible, extend the contract's protections to whatever remains (45 CFR 164.504(e)(2)(ii)(J)). HHS's sample provisions add that an agreement also could provide for the vendor to transmit the information to another business associate of the practice at termination (for example, the new billing vendor), and that the sample language is not required for compliance (HHS sample business associate agreement provisions). Neither sets a format, a deadline or a price for returning the data at termination, so settle all three in the agreement before you sign, as the guide to data ownership and exit terms explains, and repeat them in the exit letter. Medicare's late-filing clock keeps running while you wait for the files.

During the first 30 days of a MedPrecision transition, we run the new workflow alongside the outgoing vendor's with one source transmitting each claim, audit the A/R the previous company left behind, put front-end verification and authorization workflows in place, and set baseline KPI tracking (denial rate, clean claim rate, days in A/R) so performance can be compared against a fixed starting point. Legacy A/R is worked under the legacy A/R decision made in writing (see the plan below).

Whoever runs the account, compare the same metrics with the same definitions against the day-1 baseline: claims submitted, accepted and rejected, days in A/R, denial rate and reasons, and aged A/R over 90 days. Early weeks mix legacy and new work, so read the trend by payer and by month of service rather than a single week's total.

This is an illustrative example demonstrating MedPrecision's reporting methodology. It is not presented as the result of an actual client engagement. Every practice-level figure below is synthetic. No patient, practice, or payer data appears anywhere on this page. Where a public benchmark comparator is shown, it is real and cited.

The section above describes the first 30 days in outline. This is the same transition as a dated plan with named owners, delivered artifacts, and exit gates — the document a practice should expect to receive in week one, from any vendor. The windows are a general illustration of how the work can be sequenced, not a fixed MedPrecision schedule.

The plan

The legacy A/R decision, made in writing on day 21

Revenue is at risk wherever nobody owns the claims filed before cutover. Three options exist, and the plan names which one applies before the cutover date rather than after:

1. Outgoing vendor works its own A/R to completion — cleanest, but only if the contract obliges them and the termination notice period is long enough.
2. Incoming vendor works legacy A/R — requires read access to the old system and an explicit rate, since it is work on claims the incoming vendor did not file.
3. Practice works it in-house — viable only where the aged balance is small.

Whichever applies, the timely-filing clock does not pause for a transition. Fee-for-service Medicare allows one calendar year from the date of service under 42 CFR 424.44. Medicaid agencies must require claims within 12 months at most, a state can set a shorter limit, and commercial limits sit in each payer contract and any state requirement: the state-by-state timely filing database lists the limits we have verified, and the deadlines table in the A/R aging action plan shows how to read them against an aging report.

What we need from you, by when

Part of a transition sits on the client side, and a plan that lists only vendor tasks leaves that work unowned.

EDI and ERA enrollment is the critical path. Turnaround is controlled by each payer rather than by either party to the transition, and for Medicare the notice of a change of billing agent or clearinghouse has to reach the contractor in writing in advance. A plan that starts enrollment late can slip however well the rest is executed.

Ask any vendor for its transition plan in writing before you sign. It should name:

• a dated implementation schedule and a named implementation lead
• who transmits each claim, and from which date
• how legacy A/R will be worked, and at what rate
• weekly reporting from the first week
• the exit terms

The RFP and contract-terms guide covers the scope, the contract clauses and the first 120 days in detail, and the vendor evaluation scorecard turns the answers into a score.

On terms, MedPrecision's agreement runs a 12-month initial term and then month-to-month, with 60 days' written notice either way and no early-termination penalty (see pricing). Under our published terms, fees on collections posted after termination that are attributable to claims we worked remain payable, and payer and patient payments deposit directly to your own bank account. Ask every vendor on your shortlist for the same three answers in writing: term and notice, fees after termination, and where the money lands.