The first paycheck at a new job is the most important one you will ever get — not because of the amount, but because it is your one clean chance to catch a mistake before it repeats for the rest of the year. A wrong filing status, a missed 401(k) election or a forgotten local tax will quietly compound across every check until you fix it. Here is the five-minute audit, line by line.
Line 1 — Check the gross before anything else
Gross pay is the full amount before any deduction. Your salary divided by the number of pay periods should match it exactly: $75,000 paid bi-weekly is $2,884.62 per check. If the gross is wrong, nothing below it can be right. Confirm the pay frequency too — bi-weekly (26 checks) and semi-monthly (24 checks) pay the same salary but show very different per-check numbers.
Line 2 — Your pre-tax deductions came out
If you enrolled in medical, dental or vision coverage, those premiums should appear as pre-tax deductions — they lower both your income tax and your FICA. Your 401(k) or TSP election should appear too, reducing income tax but not FICA. If either is missing on check one, your benefits enrollment may not have processed; that is a same-week conversation with HR, not a "wait and see."
Line 3 — FICA is a fixed 7.65%
Social Security takes 6.2% and Medicare 1.45% of your taxable wages — together 7.65%, no brackets and no surprises at typical salaries. If the FICA line is wildly off that percentage, something above it was miscategorized. (Very high earners will see Social Security stop at the $184,500 wage base and a 0.9% Medicare surcharge above $200,000 — neither applies on a normal first check.)
Line 4 — Federal withholding matches your W-4
This is the line your W-4 controls, and the most common place a new job goes wrong. Payroll annualizes your pay, subtracts the standard deduction, applies the brackets and credits your dependents. If you claimed the wrong filing status, forgot a dependent, or never turned the form in at all, this number will be off — and it will stay off every check until you file a corrected W-4. Our pre-filled W-4 worksheet walks you through a fresh one.
Line 5 — State (and maybe local) tax
If your state has an income tax, it should appear as its own line after its own deductions and exemptions. And if you live or work somewhere with a local income tax — New York City, an Indiana county, an Ohio municipality, Philadelphia, Detroit and more — look for a separate local line. A missing local tax is not a gift; it means an under-withholding surprise is waiting for you in April.
Line 6 — Net pay should match your estimate
What is left after all of the above is your take-home. Before your first day, run your new salary through the calculator with your filing status, state and locality, then compare the result to the real stub. The two will rarely match to the penny — benefit deductions and mid-period start dates move things — but they should be close. A large gap is a flag, not a rounding error.
When something is off
Fix it in week one and it costs you a form. Leave it for six months and it costs you real money — either a surprise bill at filing time or a year of paychecks smaller than they needed to be.
- Gross wrong → payroll or your offer letter frequency.
- Pre-tax missing → benefits enrollment did not process.
- Federal wildly off → your W-4 is wrong or was never received.
- State/local missing → residency or work-location setup.
- Net far from estimate → one of the above; find it now, not in December.
Sources
- IRS Publication 15 (Circular E) — Employer's Tax Guide, withholding mechanics.
- IRS Form W-4 and instructions — Employee's Withholding Certificate.
- Social Security Administration — 2026 contribution and benefit base.