Most writing about the marriage penalty is about tax brackets. For the couples who actually pay one, that is the wrong place to look.
Every 2026 federal tax bracket for a married couple is exactly double the single-filer bracket, with one exception at the very top. The standard deduction is doubled too. So for two people earning ordinary wages, the brackets have nothing to give or take, and a calculator that models only brackets tells them their tax will not change.
The Earned Income Tax Credit is different, and it is not doubled.
The threshold that is not doubled
The EITC is a refundable credit for people on lower incomes, worth up to $7,316 a year for a family with two children. It phases out as income rises, and the income at which it starts phasing out depends on your filing status:
| Filing status | Phase-out starts | Credit gone by |
|---|---|---|
| Single or head of household | $23,890 | $58,629 |
| Married filing jointly | $31,160 | $65,899 |
| Difference | $7,270 | $7,270 |
That is the whole problem in one row. A married couple gets about $7,270 more headroom than a single filer — not twice as much. Two people who each qualified for the credit separately are treated, on marrying, as one household whose income is added together but whose allowance has barely moved.
What it costs, in dollars
Take two people earning $25,000 each, with two children between them. Unmarried, one of them files as head of household and claims the children; the other files single. Married, they file one joint return on $50,000.
| Unmarried | Married | |
|---|---|---|
| Earned Income Tax Credit | $7,082 | $3,348 |
| Net federal tax | -$9,567 | -$5,968 |
| Cost of marrying | $3,599 a year | |
Nearly all of that $3,599 is credit. Their combined $50,000 is far enough into the joint phase-out that most of the EITC disappears, where apart they were both close to the full amount. The brackets contribute almost nothing — this is a couple whose marginal rate is 10% either way.
Negative numbers in that table are refunds, not bills. Both of these households get money back; the married one just gets $3,599 less of it.
It cuts the other way too
The same un-doubled threshold produces a bonus when only one person earns. Put the same $50,000 and the same two children in a single-earner household:
Unmarried, that earner is already past the head-of-household phase-out and losing credit. Married, the higher joint threshold lets the couple keep more of it — a marriage bonus of $2,499 on identical household income. Same total, same children, opposite answer, purely because of how the income is split.
You do not need children for this
The childless EITC is small — a maximum of $664 — but its threshold is not doubled either, and it runs out sooner for a couple than for two single people. Two people earning $16,100 each collect about $526 between them filing singly. Married, their combined $32,200 is past the joint cut-off entirely and the credit is $0.
That is a $526 marriage penalty for a couple with no children, no dependants and no complications — and a bracket-only calculator reports it as zero.
What to do about it
Very little, honestly, and that is worth saying plainly rather than pretending otherwise. You cannot choose to be treated as two single filers once you are married; filing separately does not help either, because married filing separately is generally barred from claiming the EITC at all. The credit is computed on household income, and marriage makes one household out of two.
What the number is good for is planning. If you are deciding when to marry, the difference is worth knowing — marital status for a whole tax year is set by your status on 31 December, so a wedding date can move a full year's worth of credit. And if you are already married, it tells you whether your withholding is aimed at the right target.
The caveats
This models federal income tax on wage income with the standard deduction, the EITC and the Child Tax Credit. It assumes every child qualifies for both credits, which have slightly different age tests, and it cannot know about the age test on the childless credit. It does not model state income tax, and several states run their own version of this problem. The full list of what is and is not modelled is on the about page.
Every figure on this page is computed by the same engine as the calculator, against tax year 2026 figures from IRS Rev. Proc. 2025-32. Change the inputs there to see your own numbers.