A non-tax adjustment on your payslip is any line item that changes your take-home pay without changing the taxable wages your employer used to calculate withholding. It sits after the tax math is already done. Court-ordered garnishments, union dues, Roth 401(k) contributions, mileage reimbursements, and retroactive pay corrections all show up in this part of the stub. Some subtract from your check, some add to it, and none of them shift your federal income tax, Social Security, or Medicare withholding for the period.
Why “Non-Tax” Means After-Tax
Every payroll deduction is either pre-tax or post-tax, and the label decides where it lives on your stub. Pre-tax deductions come out of your gross pay before withholding is calculated, so they shrink the wage figure the IRS sees. A traditional 401(k) is the textbook case: contribute $500 out of $5,000 in gross wages, and your employer withholds tax on $4,500.
Non-tax adjustments work the opposite way. Your employer runs the full withholding calculation on your gross pay first, then applies the adjustment to what’s left. A Roth 401(k) contribution is post-tax, so you pay tax on the money now and pull it out tax-free later. A wage garnishment operates the same way mechanically: taxes come off your full earnings, then the garnishment comes out of your net. Neither one lowers the taxable wage total.
That’s the core of what the label is telling you. The dollars in this section have already been taxed (if they’re a deduction) or aren’t compensation at all (if they’re a reimbursement).
Common Post-Tax Deductions
The non-tax deductions you’re most likely to see:
- Roth 401(k) and Roth 403(b) contributions. Withheld from after-tax pay. The money grows tax-free but doesn’t reduce your current tax bill.
- Union dues. If you belong to a union, dues typically come out of net pay under a written payroll assignment you authorized.1Office of the Law Revision Counsel. 29 US Code 186 – Restrictions on Financial Transactions
- Supplemental life insurance. Employers can provide up to $50,000 in group-term life insurance tax-free. Premiums for coverage above that threshold come out post-tax.2Office of the Law Revision Counsel. 26 US Code 79 – Group-Term Life Insurance Purchased for Employees
- Voluntary disability insurance. Premiums are usually deducted after taxes. The upside: if you ever collect benefits, they’re generally tax-free.
- Payroll-deducted charitable contributions. Come out of net pay. If you want to claim the deduction on your return, you’ll need your pay stub plus a pledge card or similar record from the charity.3Internal Revenue Service. Substantiating Charitable Contributions
Because none of these lowered your taxable gross, your federal income tax, Social Security, and Medicare withholding for the pay period are unaffected. You’ve already paid tax on those dollars.
Garnishments
Garnishments are involuntary non-tax deductions. A court or government agency orders your employer to withhold part of your pay and send it to a creditor. They always come out after taxes, and the amount depends on what kind of debt is being collected.
Consumer Debt
For ordinary consumer debts like a credit card judgment, federal law caps the garnishment at the lesser of 25% of your disposable earnings for the week, or the amount your weekly disposable earnings exceed 30 times the federal minimum wage ($7.25 per hour).4U.S. Department of Labor. Fact Sheet 30 – Wage Garnishment Protections of the Consumer Credit Protection Act Whichever figure is lower is the maximum. If you earn less than $217.50 in a week, your wages can’t be garnished for consumer debt at all.5Office of the Law Revision Counsel. 15 US Code 1673 – Restriction on Garnishment
Child Support
Child support garnishments run to higher limits and take priority over everything else. If you’re currently supporting another spouse or dependent child, the cap is 50% of disposable earnings. If not, it rises to 60%. Both figures go up another 5 points (to 55% or 65%) when the order covers arrears more than 12 weeks old.5Office of the Law Revision Counsel. 15 US Code 1673 – Restriction on Garnishment If a support order already fills the allowable withholding, a lower-priority consumer garnishment on the same paycheck may be delayed.
Defaulted Federal Student Loans
The Department of Education or a guaranty agency can garnish up to 15% of your disposable pay for a defaulted federal student loan, using an administrative process that doesn’t require a court order.6Office of the Law Revision Counsel. 20 USC 1095a – Wage Garnishment Requirement The same 15% cap applies to other nontax debts owed to the federal government under a separate administrative wage garnishment statute.7Office of the Law Revision Counsel. 31 USC 3720D – Administrative Wage Garnishment You must get written notice at least 30 days before the garnishment starts, and you have the right to inspect records and request a hearing on the amount owed.
Non-Tax Additions: Reimbursements
Not every non-tax adjustment is a subtraction. When your employer pays you back for a business expense, that money often shows up in the same section of your stub as a positive number. It isn’t compensation, so it isn’t taxed.
For a reimbursement to stay tax-free, the arrangement has to qualify as an accountable plan. The IRS requires three things: the expense must have a business connection, you must substantiate it to your employer (receipts, mileage logs, and so on), and you must return any amount that exceeds the documented expense.8Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide Amounts paid under a qualifying accountable plan aren’t subject to income tax, Social Security, Medicare, or federal unemployment tax.
Three types show up most often:
Mileage. The IRS standard business mileage rate for 2026 is 72.5 cents per mile.9Internal Revenue Service. IRS Sets 2026 Business Standard Mileage Rate at 72.5 Cents Per Mile, Up 2.5 Cents As long as your reimbursement doesn’t exceed the standard rate multiplied by your documented business miles, it’s a non-tax addition. Anything above that rate becomes taxable income.
Per diem. Per diem covers lodging and meals when you travel for work. Rates are set by the General Services Administration and vary by location.10U.S. General Services Administration. Per Diem Rates For FY 2026, the standard CONUS rate is $110 for lodging plus $68 for meals and incidental expenses, or $178 a day; high-cost cities carry higher rates. Stay at or below the GSA rate for the location and the full per diem posts as non-taxable.
Cell phone and remote work costs. If your employer requires you to use a personal phone for work, reimbursements for reasonable phone expenses are nontaxable, and the IRS doesn’t require tracking business versus personal use where business use is the primary reason.11Internal Revenue Service. IRS Issues Guidance on Tax Treatment of Cell Phones Home internet reimbursements can qualify too, but the employer needs a policy that ties the expense to business necessity. A reimbursement that looks more like a salary supplement than a documented business expense can be reclassified as taxable wages.
Retroactive Pay Corrections
This is where most people first notice the phrase “non-tax adjustment” and start wondering what happened. Payroll made an error, and the fix appears on the current stub instead of being run through as a recalculation of an earlier period.
If you were underpaid, your employer can add the shortfall to your current check as a non-tax adjustment. Withholding was already calculated on the higher gross that should have been paid, so adding the cash difference now brings your take-home in line without disturbing prior-period tax reporting. Employers are required to pay for all hours actually worked, and these adjustments are one way of staying compliant with that obligation.12U.S. Department of Labor. Fact Sheet 22 – Hours Worked Under the Fair Labor Standards Act
If you were overpaid, expect a negative non-tax adjustment on a future check to recover the excess. The original taxes were already paid on the inflated gross, so the correction targets the net cash. There’s no single federal cap on how much an employer can recover per paycheck, but many states restrict these deductions, often by prohibiting any recovery that would push you below minimum wage for the period, or by capping the amount at a set percentage of earnings. Written consent is generally required, and spreading the recovery across multiple pay periods is standard practice.
What to Check on Your Stub
Pay stub formats vary, but non-tax adjustments usually sit in their own section, separate from pre-tax deductions and tax withholdings. Look for labels like “post-tax deductions,” “other deductions,” “non-tax adjustments,” or “reimbursements.” Each entry should carry a description, a current-period amount, and a year-to-date total.
Read every line against something you know:
- Roth contributions should match the percentage or dollar figure in your enrollment elections.
- Garnishment amounts should match the order your employer received, and should respect the federal caps above.
- Reimbursements should tie back to expense reports, mileage logs, or travel you actually took.
- Retroactive adjustments should correspond to a specific prior-period error you can identify.
If a line doesn’t match, contact payroll before the next pay cycle. A reimbursement labeled as non-taxable that doesn’t correspond to a real business expense is worth flagging in particular: the IRS can reclassify a mislabeled “reimbursement” as taxable wages, and if that happens after the fact, the income tax bill lands on you. Catching an error in the current period is far simpler than unwinding months of incorrect stubs later.