What Is SIT on Your Paystub? State Income Tax Explained
SIT is state income tax withheld from your wages. Why the amount differs from federal tax, what drives it and why some stubs show no SIT line at all.
SIT on a pay stub is state income tax: the amount your employer withheld on behalf of the state where you work or live. It sits near the federal income tax line and is often confused with it, though the two are calculated under completely separate rules.
Why It Is Not Simply a Smaller Federal Tax
Federal withholding follows the IRS tables and your Form W-4. State withholding follows your state's own schedules and, in most states, a separate state withholding certificate. The definitions of taxable wages can differ too: a deduction that reduces federal taxable wages does not always reduce state taxable wages.
That is why the ratio between the two lines varies between employees and why copying a colleague's setup is poor guidance.
The Certificate Most People Skip
California has Form DE 4, Georgia has Form G-4, Arizona has Form A-4, and so on. Several states accept the federal W-4 as a fallback, but accepting it is not the same as it being correct for your situation. If you have never filed a state certificate, your SIT is being calculated on a default basis, which is one of the most common reasons an employee owes state tax despite withholding on every paycheck.
When There Is No SIT Line
Nine states do not tax wage income, so stubs from those states show no SIT at all. If you live in one state and work in another, you may see withholding for the work state, the resident state, or both, depending on whether the states have a reciprocity agreement. That combination is worth checking early in a new job rather than at filing time.
I go through the state-by-state variation and what to do when two states both appear on your stub in my explainer on SIT withholding for Online Paystub.
Where It Ends Up
Your year-to-date SIT figure becomes Box 17 on your W-2, with the corresponding state wages in Box 16. Before filing a state return, compare the two against your final pay stub of the year; they should agree exactly, and any gap is a question for payroll.
