Paycheck Deduction Checker
Enter what your pay stub says and see whether each deduction is right. Checks Social Security, Medicare, and federal withholding against 2026 IRS rules.
Paycheck Deduction Checker
Copy the numbers off your stub
Type in what your pay stub actually says for one pay period. Nothing you enter leaves your browser. Tax year 2026.
Biweekly is 26 checks a year. Semimonthly is 24. They are not the same, and payroll uses the count to annualize your wages.
The gross for this one check. A check with heavy overtime annualizes as if every check were that big, so federal withholding on it looks high and evens out over the year.
Post-tax items: Roth 401(k), union dues, garnishments, local or city tax, and state paid leave premiums such as CA SDI, NY PFL and SDI, NJ SUI, SDI and FLI, OR Paid Leave, CO FAMLI, MA PFML, WA PFML, and WA Cares. Those premiums are not income tax.
Reduces the wages your federal income tax is figured on, but not your Social Security and Medicare wages. Roth 401(k) is post-tax and belongs in Other deductions.
Section 125 cafeteria plan money. Reduces both wage bases: federal income tax wages, and Social Security and Medicare wages.
Your W-4 (drives the federal income tax check)
These are the three boxes on the W-4 and the three schedules in IRS Pub. 15-T. Married filing separately uses the single schedule for withholding.
Check this only if it is checked on the W-4 you actually filed.
If your stub shows W-4 allowances instead of these steps, you are on a pre-2020 W-4. Payroll uses a different table for those, so this federal estimate will run high or low. The fix is to file a current W-4.
Advanced: year-to-date wages and your state
The 2026 cap of $184,500 is annual and cumulative, never sliced per paycheck. Above the cap, $0 of Social Security on a check is correct, not an error.
Take it from a prior stub (state tax divided by taxable wages) or your state revenue department table. Left blank, the state row stays informational.
Enter the gross pay printed on your stub to start.
2026 estimate. Federal withholding is modeled with the IRS Pub. 15-T percentage method for automated payroll systems. Your employer may legally use the wage bracket method, the cumulative wages method, or a part-year method, any of which produces a slightly different number on the same wages. State income tax is not predicted here, because state rules and state withholding certificates vary too much to model from a filing status alone. This is a plausibility check, not a legal audit.
The two checks that tell you whether your paycheck is correct
The first check is pure arithmetic, and it holds no matter what. Gross pay minus every deduction printed on the stub has to equal the net pay printed on the stub. That identity is true in all 50 states, at any income, under any W-4, with no tax modeling involved. When it fails, the stub contradicts itself and payroll has some explaining to do.
The second check asks whether the rates themselves are plausible. Social Security and Medicare are fixed statutory percentages, so they are verifiable to the cent once you know the right wage base. Federal income tax can be estimated from your W-4, but employers may legally use any of several withholding methods, so this tool gives that line a tolerance band instead of a hard pass or fail. A miss on the federal line is usually a W-4 issue, not a payroll error.
Take a $2,500 biweekly check for a single filer with no pre-tax deductions. Social Security should be $155.00 (6.2 percent), Medicare $36.25 (1.45 percent), and federal income tax $216.15 under the percentage method. Add $95 of state tax and the net should land at $1,997.60. If the stub says $1,850, roughly $148 is unaccounted for and payroll owes you an explanation.
What each line on your stub should be in 2026
Social Security is 6.2 percent of your Social Security wages, up to a wage base of $184,500 for 2026. That cap is annual and cumulative, not sliced across your paychecks. Someone on pace for $300,000 pays the full 6.2 percent on every check until cumulative wages reach $184,500, then pays $0 for the rest of the year, with one partial check at the crossover.
Medicare is 1.45 percent of the same wages with no cap. Above $200,000 paid by a single employer in the calendar year, that employer must also withhold an extra 0.9 percent, regardless of your filing status. Your own liability uses a filing status threshold instead ($250,000 for married filing jointly), so a married single-earner household is correctly over-withheld during the year and gets the difference back at filing.
Federal income tax runs through the annualize, tax, de-annualize sequence in IRS Publication 15-T. Payroll multiplies this check's taxable wages by your number of pay periods, applies your W-4 Step 4 adjustments, subtracts the 2026 standard deduction ($16,100 single, $32,200 married filing jointly, $24,150 head of household), walks the brackets, subtracts Step 3 credits, and divides back down. State income tax is the one line no calculator should promise to predict. This tool reports it rather than grading it, unless you supply your own rate.
Pre-tax deductions, and the one that does not lower your FICA
This is the distinction most stub explainers get wrong, and it is why the tool asks for two separate pre-tax fields. Traditional 401(k), 403(b), and 457(b) deferrals are excluded from federal income tax wages but stay in Social Security and Medicare wages under IRC 3121(v)(1). Section 125 money (health, dental, vision, FSA, and payroll HSA) comes out of both wage bases. Roth deferrals reduce neither, because they are post-tax.
The same $2,500 biweekly check, three ways. With no pre-tax deductions: federal wages $2,500, FICA wages $2,500, Social Security $155.00, Medicare $36.25, federal tax $216.15. With $250 going to a traditional 401(k): federal wages drop to $2,250 and federal tax falls to $186.15, but FICA wages stay at $2,500, so Social Security is still $155.00 and Medicare is still $36.25. With $250 going to health premiums instead: federal tax is the same $186.15, but FICA wages also drop to $2,250, so Social Security falls to $139.50 and Medicare to $32.63.
Enter a Roth deferral in the retirement field and you will see a false alarm on the federal line, because the tool will expect tax on wages that were never sheltered. See the 401(k) Paycheck Impact Calculator for the retirement side and the HSA and FSA Paycheck Impact Calculator for the Section 125 side.
What to do when a line is off
There are only two things it can be. A payroll error is anything that breaks the arithmetic, or a Social Security or Medicare line more than a couple of percent off the statutory rate. Report it to payroll in writing, with the line named and the figure you expected. Most employers fix a confirmed error within a pay period or two, and in many states they are required to.
A W-4 problem looks different: the arithmetic reconciles, FICA is exact, and only the federal line drifts. Under-withholding usually traces to a stale W-4, a second job where both employers assume they are your only one, or a Step 3 credit that no longer applies. Over-withholding usually traces to an unrecorded Step 4(c) amount or a filing status left at single after a marriage. File a new W-4 and size the Step 4(c) amount with the W-4 Withholding Planner. If the check included a bonus or commission withheld at the flat 22 percent supplemental rate, the Bonus Tax Take-Home Calculator explains the gap, and the Net to Gross Salary Calculator runs the same math in reverse.
The app goes further than a single stub: per-state withholding tables, state items such as CA SDI and NY PFL, year-to-date FICA tracking, and saved profiles for comparing two jobs side by side. Download the Stub44 Salary Calculator app.
Frequently Asked Questions
Common questions about paycheck deduction checker
How do I know if my paycheck is correct?
Two checks. First the arithmetic: gross pay minus every deduction on the stub has to equal the net. Second the rates: Social Security should be 6.2 percent and Medicare 1.45 percent of your FICA wages, and federal income tax should match what the IRS percentage method produces from your W-4. If the arithmetic breaks, something on the stub is wrong. If only the federal line is off, it is usually your W-4 rather than a payroll error, and the W-4 Withholding Planner sizes the fix.
Why is my federal withholding so low or zero?
A handful of things do this. Dependent credits in Step 3 of the W-4 can wipe the tax out entirely. Income low enough that annualized wages fall under the 2026 standard deduction, $16,100 single or $32,200 married filing jointly, produces $0 by design. Large pre-tax deductions cut the taxable wages the tax is figured on. Exempt on the W-4 stops federal withholding outright. And if the Step 2(c) box is checked on both jobs, each employer assumes the other is withholding more. Run the numbers through the W-4 Withholding Planner to see whether you land on a balance due in April.
Should Social Security be exactly 6.2 percent of my gross pay?
6.2 percent of your Social Security wages, which is not always your gross. Section 125 health premiums, FSA, and payroll HSA come out first and lower it, as the HSA and FSA Paycheck Impact Calculator shows. A 401(k) deferral does not. And once your cumulative Social Security wages hit $184,500 for 2026, the line correctly drops to $0 for the rest of the year.
Why does my 401(k) lower my federal tax but not my Social Security?
Because Congress wrote it that way. Elective deferrals to a traditional 401(k), 403(b), or 457(b) are excluded from federal income tax wages but stay in Social Security and Medicare wages under IRC 3121(v)(1). Section 125 cafeteria plan money such as health premiums, FSA, and payroll HSA comes out of both. That is why this tool asks for the two separately, and why the 401(k) Paycheck Impact Calculator shows a smaller take-home hit than the deferral itself.
What if my employer took out the wrong amount?
Tell payroll in writing with the specific line and the figure you expected. Most employers correct a confirmed error within one or two pay periods, often on the next check. Under-withheld federal tax is not an employer error you can recover from them: it lands on your 1040 as a balance due, so fix it forward with a new W-4 sized in the W-4 Withholding Planner. Wage underpayment is a different matter, and your state labor department can intervene.
Why is more Medicare coming out of my paycheck than 1.45 percent?
You have passed $200,000 in wages from that employer this year. Employers must withhold an extra 0.9 percent above $200,000 regardless of your filing status. Your actual liability uses your filing status threshold instead, $250,000 if married filing jointly, so a married single-earner household gets some of it back at filing. Nothing is broken there, so this checker will not flag it.
Does a Roth 401(k) show up as a pre-tax deduction?
No. Roth contributions come out after tax, so they lower your net pay without lowering any taxable wage base. Enter them under other deductions, not in the retirement field. Putting a Roth deferral in the pre-tax box is the fastest way to make a correct stub look like it has too much federal tax withheld. The 401(k) Paycheck Impact Calculator covers the traditional side.
Why does this tool not check my state tax?
Because state withholding runs on a state-specific certificate, state allowances, local and county taxes, and reciprocity rules. Guessing at all of that from a filing status alone would flag correct paychecks as wrong. What the tool will do is flag a state tax line in a state with no wage income tax, and check the state row if you enter your own rate. For full per-state withholding tables and state items such as CA SDI and NY PFL, use the Stub44 Salary Calculator app.