Step 1 of 7 · The return and the employer
Report wages, tips, federal income tax withheld, and Social Security and Medicare taxes for the quarter. Figures are computed by your payroll system; this form records and files them.
Correcting a quarter you already filed? That is Form 941-X, a separate return.
A quarter can be filed once it has ended. Form 941 reports the wages paid in a quarter and the tax withheld from them, so the quarters still to close are not selectable yet — each is listed with the day it ends.