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Box 3 – Patient's Birth Date and Sex

On the CMS-1500 claim form, Box 3 carries the patient's date of birth and sex — two of the values payers lean on hardest when matching a claim to the right member. This guide explains what the box holds and where Pabau takes the values from.

NOTE: This article is part of the US Insurance Billing Additional Resources series, which walks through every box of the CMS-1500. If you are new to claims in Pabau, start with Creating a US Professional (CMS 1500) Claim.

Box 3 — Patient's birth date and sex

Box 3 of the CMS-1500 claim form with the patient's birth date cells and the sex checkboxes

Box 3 splits into date cells for the patient's birth date and a pair of SEX checkboxes, M and F — the form itself carries only those two. The sex reported here is the one the insurance company has on file for the patient, which is not always the same as how the patient describes themselves. Both values are required on electronic claims.

How Pabau fills it

Both values live in the Patient section of the claim editor, which is labeled with the CMS-1500 boxes it covers (2–5): a Date of birth field and a Sex select offering M, F, and U. They prefill from the client record when the invoice issued to the insurer becomes a claim, you can correct them on the claim before validating or sending, and any Patient field left blank falls back to the client record at validation.

The Patient section of a Pabau claim with the Date of birth field and the Sex select

On the printed form (Export > Print), the date of birth lands in the MM, DD, and YYYY cells and the matching sex checkbox is marked. When the claim's sex is U, Pabau deliberately leaves both checkboxes empty — the paper form has no third option, so an unmarked pair is the correct way to represent it.

On the electronic claim: the two values are sent to Claim.MD as the patient date of birth and patient sex (M, F, or U).

TIP: Payers match claims against the date of birth and sex they hold for the member. If the patient's insurance paperwork disagrees with your records, bill with what the payer has on file — and have the patient correct it with their insurer — to avoid an avoidable rejection.

For the coverage and member-ID side of the claim, see Box 1 – Insurance Coverage Type.