Sick Leave Wages

I think this is what you are asking about:

They should already be part of the W2 boxes.

https://www.lockton.com/insights/post/irs-addresses-w-2-reporting-for-ffcra-sick-and-fmla-leave

And:

https://www.journalofaccountancy.com/news/2020/jul/report-coronavirus-paid-sick-family-leave-employees.html

"Employers will be required to report payments to employees either on box 14 of Form W-2, Wage and Tax Statement, or in a separate statement. The guidance provides employers with language to use on the Form W-2 or in the statement to employees.

Employers must separately state the total amount of qualified sick leave wages paid because the employee was quarantined or diagnosed with COVID-19, the total amount of qualified sick leave wages paid because the employee was caring for a sick individual or for a child (or for other similar reason), and the total amount of qualified family leave wages paid.

This reporting provides employees who are also self-employed with information necessary for properly claiming qualified sick leave equivalent or qualified family leave equivalent credits under the Families First Act."

https://www.irs.gov/pub/irs-drop/n-20-54.pdf