What this calculator does
When you have two jobs at the same time, or you and your spouse both work and file jointly, each employer withholds federal income tax as if its paycheck were your only income. Each job then applies the full standard deduction and the low tax brackets, so together they often withhold too little. Enter both yearly pays and how often each job pays, and the calculator compares your 2026 federal income tax with what three ways of filling in Form W-4 would withhold.
How it is worked out
Tax for the year = the 2026 brackets applied to both pays together minus the standard deduction, minus the child tax credit and the credit for other dependents. Withholding uses the IRS Publication 15-T percentage-method tables for 2026, the same ones payroll systems use. Example: a married couple filing jointly earns $70,000 and $50,000, both paid every two weeks, with no dependents. Their 2026 tax is $10,040. If neither W-4 is adjusted, the two jobs withhold about $5,820, leaving about $4,220 to pay in April. Checking the Step 2(c) box on both W-4s withholds about $10,390. Adding $163 per paycheck in Step 4(c) on the $70,000 job brings withholding to about $10,058.
The three ways on Form W-4
- Step 2(c) box on both W-4s: the simplest choice, allowed when there are only two jobs in total. The 2026 Form W-4 says it is generally more accurate than the Multiple Jobs Worksheet when the lower pay is more than half of the higher pay; otherwise the worksheet is more accurate.
- Extra withholding in Step 4(c): put the extra amount per paycheck on the W-4 for the higher-paying job, and leave the other W-4 at its basic entries. This calculator works out the amount; the Multiple Jobs Worksheet in the W-4 instructions does the same with tables.
- IRS Tax Withholding Estimator: the most accurate choice when you have other income, deductions or credits.
Fill in Steps 3 to 4(b), including dependents, on the W-4 for only one job; the form says withholding is most accurate when that is the highest-paying job (IRS Form W-4, 2026). Give each employer its new W-4; the change starts with a later paycheck.
Frequently asked questions
Why do I owe tax when I have two jobs?
Each employer withholds as if its job were your only one, so each applies the standard deduction and the lowest brackets. Together your income reaches higher brackets that neither employer withholds for.
Should both spouses check the Step 2(c) box?
If you choose the checkbox, check it on both W-4s. It is generally the more accurate choice when the lower pay is more than half of the higher pay.
Which W-4 gets the extra withholding?
The one for the higher-paying job, in Step 4(c), as an amount per paycheck.
Does this include Social Security and Medicare?
No. Those are withheld correctly by each job on its own. This checkup is for federal income tax only.
Is my information saved?
No. The numbers stay on this page.