Updated October 17, 2026. Quick answer: The Third-party sick pay checkbox in box 13 of Form W-2 is checked by a third-party sick pay payer, such as an insurer, filing a W-2 for an insured’s employee, or by an employer reporting sick pay paid by a third party. If you see it checked, the W-2 includes sick pay that did not come directly from your employer. The instructions point to section 6 of Pub. 15-A for the reporting rules.
What the Third-party sick pay checkbox says
The third checkbox in box 13 is the narrowest of the three. The instruction reads: “Check this box only if you are a third-party sick pay payer filing a Form W-2 for an insured’s employee or are an employer reporting sick pay payments made by a third party.” It then points elsewhere for the rules: “See section 6 of Pub. 15-A.” The checkbox is not about how sick you were or how long you were out. It describes who paid and who filed the form.
The other box 13 checkboxes, and the rest of the boxes in the range, are explained in the W-2 boxes 10 to 20 guide.
Two ways the box can end up checked
The text describes two situations in the same sentence. In the first, the filer is the third party, for example an insurance company that paid sick pay to someone covered by a plan. In the second, the filer is the employer, who is reporting sick pay that a third party paid. The Special Reporting Situations section of the instructions explains how the second situation comes about: “If you had employees who received sick pay in 2025 from an insurance company or other third-party payer and the third party notified you of the amount of sick pay involved, you may be required to report the information on the employees’ Forms W-2.”
The instructions also cover the case where the employer was not told: “If the insurance company or other third-party payer did not notify you in a timely manner about the sick pay payments, it must prepare Forms W-2 and W-3 for your employees showing the sick pay.” So a W-2 for sick pay can arrive from an insurer rather than from the employer you worked for. Either way, the form is a normal Form W-2, and the other boxes should be read the way they are on the pages of the W-2 boxes 10 to 20 guide.
How this connects to box 12 code J
The box 12 instructions on the form include a code for a related situation: “Nontaxable sick pay (information only, not included in box 1, 3, or 5)”. The payer-side instruction for the same code describes it as sick pay “paid by a third party and was not includible in income (and not shown in boxes 1, 3, and 5) because the employee contributed to the sick pay plan”. Code J is a separate item in box 12 and is not set by the box 13 checkbox. The full list of box 12 codes is on the box 12 codes page.
What to look at on your own form
If the Third-party sick pay box is checked on a W-2 you received, three things on the form are worth checking against your records. First, the payer named in the employer boxes at the top of the form: it may be an insurer instead of the company you worked for. Second, the wages and tax boxes, which are set out on the Form 1040 page in terms of where they land on the return. Third, any federal income tax withheld in box 2, compared with your own pay records.
For the reporting rules themselves, the instructions send the filer to Pub. 15-A, not to the employee. If the box is checked and you do not recognize the payer, the payer named on the form is the one to contact. The W-4 you gave your employer is a different topic and is on the Form W-4 page.
Why it matters to the person reading the form
When the box is checked, the form may come from the payer of the sick pay and not from your employer. Keep the sick pay statement or benefit notice you received from the insurer with the W-2, so the amounts on the form can be matched to the payments you actually received during the year.
Edition and box numbers
The primary read for this page is the 2025 edition of Form W-2, the one an employee receives in early 2026 for tax year 2025, together with the 2025 General Instructions for Forms W-2 and W-3 and the Notice to Employee and Instructions for Employee printed on the form. The 2026 edition was the one irs.gov served as current on October 17, 2026; the 2025 files come from the IRS prior-year archive. The third-party sick pay checkbox text is the same in the 2026 edition of the General Instructions, which reads “Check this box only if you are a third-party sick pay payer filing a Form W-2 for an insured’s employee or are an employer reporting sick pay payments made by a third party.” Box 13 is box 13 in both editions. Check the tax year printed on the form you received, because the box layout can change from one year to the next.
Common mistakes
- Assuming the box means your employer paid the sick pay. The instruction covers a payer who is “a third-party sick pay payer filing a Form W-2 for an insured’s employee”.
- Confusing the checkbox with box 12 code J. The form describes code J as “Nontaxable sick pay (information only, not included in box 1, 3, or 5)”, which is a separate entry from the box 13 checkbox.
- Expecting the checkbox to carry the rules. The instruction itself says “See section 6 of Pub. 15-A.” for the reporting rules.
Related: the box 12 codes page, the Form 1040 page, the Form W-4 page, and the box 12 vs box 1 page.
Sources
- General Instructions for Forms W-2 and W-3 (2025): IRS archived PDF (irs.gov)
- Form W-2, Wage and Tax Statement (2025), with the Notice to Employee and Instructions for Employee: IRS archived PDF (irs.gov)
- General Instructions for Forms W-2 and W-3 (2026): https://www.irs.gov/pub/irs-pdf/iw2w3.pdf
Read from the IRS documents linked above on October 17, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer, the account provider or the IRS is the right place to confirm anything consequential.