Legacy A/R is the most commonly mishandled part of a billing transition, and the term governing it is usually absent from both contracts. The outgoing vendor has little incentive to work claims they may not be paid for, and the incoming one has no context for them.
Switching billers is routine. The claims already in flight when you switch are not, and they are where transitions quietly lose money.
The gap nobody owns
Your outgoing biller has little incentive to work claims after notice. Their fee typically stops, their staff are reassigned, and the effort produces revenue for a relationship that is ending.
Your incoming biller did not submit those claims, does not know their history, and is usually compensated on what they bill going forward. Legacy A/R is somebody else's mess arriving without documentation.
So a book of receivables sits between two parties, both of whom have reason to treat it as the other's problem. Meanwhile filing and appeal windows keep running.
What to settle before notice
- Who works the tail, for how long, at what rate. Both contracts should say. Most say nothing.
- Data access. Claim-level history, not summary reports, and access continuing past the end date.
- Payer enrollment continuity. ERA and EFT routing changes are the classic cause of the post-transition payment gap.
- A cutoff rule. By date of service or by submission date — stated, so nothing falls between definitions.
Expect a dip
Even a clean transition produces a temporary drop in collections. Enrollment takes time, the new team is learning your payers, and the old queue is being worked by nobody for a period. Planning for it is the difference between a soft quarter and a crisis.
Legacy A/R is harder work than current claims and is usually priced separately for that reason. A vendor who quotes their standard rate on your aged book has either not looked at it or is not planning to work it.
Split the cohort by submission date
Claims submitted before the cutover belong to the outgoing vendor; claims after belong to the incoming one. That single rule keeps accountability clear and stops both parties attributing every disappointing number to the transition.
Measure each on its own cohort, not on the blended total.
Get the working notes, not just the data
An export of open claims tells you the balance. It does not tell you which have appeals pending, which were promised a reprocess, or which the payer has already reviewed twice.
Ask for the follow-up notes explicitly; they are the part most likely to be withheld and the part that determines whether the claims are workable.
Write it down before notice
Rate, duration, scope and reporting for the run-out period, agreed in writing while the relationship is still intact.
Common questions
- Who works my A/R when I change billing companies?
- Whoever the contract says. If neither contract addresses it, the answer in practice is usually nobody, and the claims age until they are unrecoverable.
- What is a run-out arrangement?
- An agreement for the outgoing vendor to continue working claims already submitted, for a defined period and at an agreed rate.
- Should the new vendor take over old claims?
- They can, but they lack the history — what was appealed, what was promised, who was spoken to. Price and scope that explicitly rather than assuming.
- How long should the overlap be?
- Long enough for submitted claims to resolve, commonly a quarter. A clean cutover date sounds tidy and creates a gap.
- When should this be negotiated?
- Before notice is given. Once you have terminated, your leverage to agree a run-out arrangement is largely gone.
Denials Piling Up?
We handle the revenue cycle end to end — coding by certified coders, claim submission, denial management and appeals, and A/R follow-up, with six reported numbers every month.