Answer the three questions above.
The claim frequency code — also called the resubmission code, or the third digit of the type of bill on institutional claims — tells the payer what this submission is. Nearly all billing uses three of them.
| Code | Means | Use it when |
|---|---|---|
| 1 | Original claim | First submission — or a resubmission where the payer has no record of the original |
| 7 | Replacement of prior claim | Something you submitted was wrong and you want the corrected version paid |
| 8 | Void / cancel prior claim | The claim should not exist at all — wrong patient, wrong payer, true duplicate |
The distinction between 7 and 8 is simply whether the claim should exist. Code 7 says “this claim was right to submit but wrong in its detail — here it is again, corrected.” Code 8 says “withdraw this claim entirely.” A replacement is adjudicated and can pay; a void cannot.
One point that trips people up: code 7 replaces the entire claim, not the line you changed. You resubmit every service line with the correction applied. Sending only the corrected line replaces the whole claim with that single line, and everything else you originally billed disappears.
This is the most expensive confusion in the whole process, and the tool asks about it first for that reason.
A corrected claim fixes something you got wrong — a transposed code, a missing modifier, wrong units, the wrong date of service, an unspecified diagnosis where the record supports a specific one. You are not arguing with the payer; you are giving them accurate information they never had.
An appeal disputes a decision the payer made about a claim you submitted correctly — a medical necessity denial, a bundling determination, an authorisation dispute. Nothing about your claim was wrong, so there is nothing to correct.
Send a corrected claim for a medical necessity denial and it will deny again, having consumed weeks of your filing window. Send an appeal for a missing modifier and the payer will tell you to submit a corrected claim, having consumed the same weeks. Where the record genuinely supports a more specific code, the corrected claim is almost always the faster route — it goes back through normal adjudication rather than a review queue. Where the payer made a judgement, use the appeal letter generator and see how to appeal an insurance denial.
| Frequency code | Payer claim control number | |
|---|---|---|
| CMS-1500 (paper) | Box 22, left side — Resubmission Code | Box 22, right side — Original Ref. No. |
| 837P (electronic) | CLM05-3, loop 2300 | REF*F8, loop 2300 |
| UB-04 (paper) | Third digit of the Type of Bill — e.g. 117, 118 | Box 64 — Document Control Number |
| 837I (electronic) | CLM05-3, loop 2300 | REF*F8, loop 2300 |
On institutional claims the frequency code is not a separate field at all — it is the last digit of the type of bill. A hospital outpatient replacement claim is 117; the void is 118. Change the third digit and you have changed the frequency.
If you take one thing from this page: frequency codes 7 and 8 both require the payer’s claim control number for the original claim, and omitting it is the single most common reason corrected claims fail.
You will see it worded as some variant of:
Payer claim control number is required when the claim frequency code is 7 or 8. 2300.REF*F8
The number itself goes by several names depending on the payer — ICN (internal control number), DCN (document control number), CCN, or simply the claim number. It is printed on the remittance advice or explanation of benefits for the original claim. Pull it from there, not from your practice management system's internal claim ID, which is a different number entirely and will not match.
Note that this is a rejection, not a denial. The claim never reached adjudication, so there is no appeal to file and no remittance to work — you simply resubmit with the control number attached. But the clock does not stop while it sits rejected, which is why these are worth catching in your scrubber rather than in your work queue.
A corrected claim is not exempt from timely filing, and the window is frequently shorter than the original one. Many payers run the corrected-claim clock from the date of the original remittance rather than the date of service — Cigna, Aetna, Humana and UMR all publish separate corrected-claim windows, and they are commonly 90 to 180 days.
The trap is a claim that bounces: you submit frequency 7, it rejects for a missing control number, it sits in a work queue, and by the time someone resubmits it correctly the corrected-claim window has closed on a claim that was always payable. Work the timely filing calculator against the remittance date, not the service date, and see the timely filing limits guide for payer-by-payer windows.
Most people working corrected claims also want the full corrected claim guide, the timely filing calculator for the resubmission deadline, the appeal letter generator when it turns out to be an appeal rather than a correction, and the denial code lookup to work out which of the two you are actually dealing with. For secondary claims see billing secondary insurance.
Clean resubmissions, control numbers attached first time, and corrected-claim windows tracked — we do this for practices across the United States.
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