A post-tax row is one subtracted after the tax amounts have been computed, so it appears in the lower part of the deduction block and never changes the figures above it. Roth contributions inside a retirement plan, union dues, term life premiums, charitable giving through payroll and many arrangements handled by an employer live in this group.
What it controls is only the deposit. Because the base the tax rows ran on was fixed before this row was touched, the same gross produces the same tax amounts whether the row exists or not, and the whole effect lands on the last line. That makes it the least visible change on the document: nothing above the row moves.
The mix-up runs in both directions. A health premium that should be pre-tax but is processed after tax leaves the deposit smaller than the plan implies while every tax row still looks correct, which is easy to miss for months. Garnishment, at the other end, sits in the same visual group as elected items but is not one, and it applies after taxes by design.
Across a year the group accumulates in the deduction columns without touching the tax columns, so the two rungs of the year-to-date ladder stay separable and the after-tax sum is easy to read off. Retirement plans cap this kind of contribution annually, on figures published each year, and a plan that hits its cap mid-year produces a row that simply stops while the gross beside it is unchanged.
Roth Contribution After the Tax Rows
| Line | Amount |
|---|---|
| Gross pay for the period | $1,500 |
| Social Security at 6.2% | −$93 |
| Medicare at 1.45% | −$22 |
| Federal income tax withheld | −$150 |
| Roth retirement contribution (post-tax) | −$200 |
| Net pay for the period | $1,035 |
The Roth row is the last subtraction and the only one that changed nothing above it: the two fixed-rate rows ran on the full 1,500 exactly as they would have without it. Total deductions of 465 leave a deposit of 1,035. Figures are illustrative for one period and belong to no real pay record.
Frequently asked questions
Do post-tax deductions lower my taxes?
They do not lower the base the tax rows are computed on, and that is the defining property of the group rather than an incidental one. The subtraction happens once the amounts above it are fixed, so the deposit shrinks and every tax line stays where it was. Roth-style retirement contributions are the common case, where the deferral of tax is arranged at the other end of the plan instead.
Is a garnishment a pre-tax or post-tax deduction?
It is applied after the required tax rows, which places it in this group for the purpose of reading the document, and its limit is expressed as a share of what remains after those subtractions rather than of gross. That ordering is why a period carrying an order alongside a large bonus behaves differently from what a division by gross would predict. The paperwork behind the row comes from whoever issued the order.
Why do I have both a pre-tax and a post-tax benefit row?
Because a plan can contain both kinds of line at once. A retirement arrangement commonly shows a traditional deferral above the tax group and a designated Roth deferral below it, taken from the same paycheck and printed on separate rows. Two rows that look like duplicates of each other are often exactly this pair, and the amounts above them reveal which is which.
Where to read on
- the group applied above the tax rows, on the same period
- both categories compared line by line
- the full deductions guide, including which rows are voluntary
- the final line every row in this group lands on
- generate a pay stub with both deduction groups
- garnishment and total deductions in the 25-term glossary