Internal control number (ICN): the claim number Medicaid assigns, and when you need it

What an ICN is

An internal control number is the payer’s own reference for one claim. The payer assigns it when the claim is accepted into processing, and every later step, from payment to adjustment to appeal, is tracked under it. Fixing a claim the payer already processed starts with this number, as the guide to corrected and voided claims explains.

Payers call it different things. Indiana’s provider portal shows a “Claim ID,” and the same number appears as “ICN” on the Indiana remittance. The Texas remittance and status report labels it the claim number and describes it as the 24-digit Medicaid ICN. Arizona’s AHCCCS calls it the claim reference number. In the X12 remittance it is the payer claim control number, the field Nevada’s 835 guide fills with its own ICN. Medicare’s claims system assigns either an ICN or a document control number to each accepted electronic claim.

Do not confuse it with your patient account number. That one is yours, taken from your own records, and payers send it back to you on the remittance so you can match their answer to your trip.

What the digits tell you

Several states build the ICN from the date received, the way the claim came in, and a batch position, so the number itself answers questions. Three states publish their formats:

Indiana’s own example shows how to read one. A professional claim sent on an 837 with no attachments and received March 1, 2019 became 2019060699215: region 20 (electronic claim, no attachments), year 19, Julian day 060, system sequence 699, and 215 for its place in the batch.

Texas puts the media source in the middle of the number, and those three digits tell an original from a correction: 030 is an electronic claim, 031 an electronic adjustment, 051 a mass adjustment, and 071 a retroactive eligibility adjustment. When a payment changes without a request from you, that segment shows why.

Formats can disagree even inside one state. Nevada’s 835 guide describes a 16-digit ICN, yet the field for a correction in its 837P guide holds 13 digits, the last paid ICN. When a payer’s guides differ, ask its EDI help desk which form it wants before you send.

Where the ICN shows up

You will see the number at three points after you bill:

1. The claim acknowledgment. Medicare’s front-end system assigns a claim control number to each accepted claim and reports it back on the 277CA, so you can check status claim by claim. A claim rejected before that point has no ICN, which is one way to tell a rejection from a denial.
2. The remittance. Every paid, denied, or adjusted claim is listed under its ICN. The remittance advice guide covers the rest of the layout.
3. The in-process list. Texas prints claims still being processed in the same format as finished ones, ICN included, so a claim can be traced before it pays.

When you need it

Keep the ICN with the trip, because three common jobs require it.

• Correcting or voiding. The ICN goes in box 22 on paper and in the payer claim control number segment of an 837P. The corrected claims guide covers the frequency codes and which ICN to cite after earlier adjustments.
• Appealing. A Texas paper appeal is a copy of the R&S Report page with the claim circled, one claim per page. The appeals guide covers deadlines and what to attach.
• Following an adjustment. In Texas, an adjusted claim is listed with EOB 00123, which names the previous claim number and the date of the report it appeared on. Each correction adds a link to the chain, and the newest number is the one that counts.

A status call goes faster with the ICN in hand as well, though the payer’s own lookup tools often answer the question without a call. The claim status guide lists them by state.