The dollars you lose in a migration are the ones you already earned.
Here is the short answer: import the full 835 remittance history alongside the 837 claim record, not just the open balance. A balance-only load looks clean on day one and quietly strips every appeal, denial reason, and payment posting your team needs to work the account. The claim history is what gets you paid. Move it whole.
Medicare gives you one calendar year from date of service to file. An import that lands mid-window and loses the original submission date can push a still-billable claim past timely filing before anyone touches it.
Two migrations start identical. Only one can still appeal in ninety days.
A denied claim is not a dead claim. It is a claim with a reason code and a filing window. Drop the 835 during import and you keep the number in the AR total but lose the one thing that lets you recover it. Here is the same account, migrated two ways.
● Balance-only import
Vendor exports an open-balance spreadsheet. One row per account, one dollar figure.
New system shows a tidy AR total. Leadership signs off. The remit history stays in the old database.
Caller opens a $4,200 balance and sees no denial reason, no CARC/RARC, no original submit date.
To appeal, they have to re-pull the old system or call the payer to reconstruct what already happened.
● History-preserving import
Vendor exports the 837 claim and every 835 remit tied to it, keyed by claim control number.
New system shows the same AR total, plus the full transaction trail behind each dollar.
Caller opens the $4,200 balance and reads CARC 197, denied for no prior auth, dated in the record.
They file the appeal with the auth on file the same day, inside the payer window.
Four layers to carry across. Skip any one and the account gets harder to collect.
Legacy AR is not a balance. It is a stack of transactions in standards you already own. Map all four and your callers walk into a migrated account knowing exactly where it stands.
The claim as submitted
Service lines, DOS, billed amounts, rendering and billing NPI, original claim control number. Your proof of what and when.
The remittance trail
Allowed, paid, adjusted, and patient-responsibility amounts, posting dates, and check/EFT trace. The audit line for every dollar.
The reason codes
The X12-maintained adjustment and remark codes that say why a line denied. Without them, an appeal is a guess.
Human touch history
Call notes, prior appeals, promised dates, and status. Free-text, so it is the first thing a lossy import drops. Carry it anyway.
Timely filing does not pause for your go-live.
Every account you migrate is somewhere on a filing or appeal clock, and the payer does not care that you switched systems. Preserving the original submission and remit dates is what keeps these windows defensible. Real 2026 references below.
One calendar year from date of service to submit a clean claim.
CMS Pub 100-04, Ch 1, §70Often 95 days to 12 months from DOS. Confirm the exact clock per program.
State Medicaid provider manualsFiling and appeal windows live in the payer agreement, commonly 90 to 180 days.
Payer participation agreementsFrom the remittance date to request redetermination. That date lives in the 835.
CMS Pub 100-04, Ch 29What actually survives each kind of import.
| Data element | Balance-only load | History-preserving load |
|---|---|---|
| Open balance | Kept | Kept |
| Original submission date (837) | Lost | Kept |
| Payment and adjustment postings (835) | Lost | Kept |
| Denial reason codes (CARC / RARC) | Lost | Kept |
| Appeal window still open? | Unknowable without rework | Visible on the account |
| Prior call notes and appeal attempts | Lost | Kept |
| Day-one workability for AR callers | Reconstruct first, then work | Work immediately |
Named guidelines, so your migration plan is defensible.
X12 837 Health Care Claim (P and I)
The ASC X12N implementation guides (TR3) for professional and institutional claims. Your legacy claim data already conforms to these, which is why a standards-based export moves cleanly.
X12 835 Health Care Claim Payment / Advice
The electronic remittance advice format carrying payment, adjustment, and denial detail with posting dates. This is the file a balance-only import throws away.
HIPAA Administrative Simplification, 45 CFR Part 162
Mandates the X12 standard transaction sets and their TR3 guides for covered entities. Migrating in these standards keeps you inside the rules and avoids re-keying.
X12 CARC and RARC
The maintained Claim Adjustment Reason Codes and Remittance Advice Remark Codes that explain every denial. Preserve them and appeals write themselves.
CMS Medicare Claims Processing Manual, Pub 100-04
Chapter 1 sets the one-calendar-year timely-filing limit. Chapter 29 governs the appeals timeline that starts on the remittance date in your 835.
State Medicaid provider manuals
Filing and appeal windows vary widely by state and program. Confirm each clock against the current manual rather than assuming a national default.
RecoveAR imports the history, not just the balance.
RecoveAR is built to migrate legacy AR the way it should move: the 837 claim, the full 835 remit trail, the CARC/RARC reason codes, and the worklog, all mapped and reconciled so your callers can work every account from day one. No reconstruction, no forfeited appeals, no dollars stranded in the old system. We map your export, prove the reconciliation, and hand you an AR file that is ready to collect.
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