Compare a couple’s tax jointly assessed versus taxed separately.
Saving from joint assessment
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Joint total tax
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Single total tax
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Your breakdown
Updates live as you type| Element | Single assessment | Joint assessment |
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The only thing joint assessment changes
When a married couple or civil partners elect joint assessment with Revenue, almost nothing about how each person is taxed changes, with one important exception. USC and PRSI stay individual: each spouse pays their own based on their own income, so those figures are identical whether you are assessed jointly or separately. The personal tax credit is the same total either way. What genuinely moves is the standard rate band. A single person keeps the 20 percent rate on income up to €44,000. A married couple gets a combined band of €53,000, plus the ability to transfer up to €35,000 of the lower earner’s unused band to the higher earner. That transferable slice is where every euro of saving comes from.
Why a €60,000 and €20,000 couple save €3,200
Picture one spouse on €60,000 and the other on €20,000, both employees. Assessed as two single people, the €60,000 earner pays 20 percent only up to €44,000 and 40 percent on the €16,000 above it. The €20,000 earner sits comfortably inside their own 20 percent band. Under joint assessment, the lower earner is only using €20,000 of their band, so the unused portion lifts the higher earner’s cut-off well past €60,000. The whole of the €60,000 now falls inside the 20 percent band. That €16,000 which used to be taxed at 40 percent is now taxed at 20 percent, and 20 percentage points on €16,000 is exactly €3,200. The USC and PRSI on both salaries are unchanged, so the entire saving is that band shift.
When you should not bother switching
The benefit evaporates when both spouses already earn above their own €44,000 cut-off. In that case there is no unused band to transfer, both partners are using their full 20 percent allocation, and joint and single assessment produce the same bill. If you both earn, say, €70,000, this tool will show a saving of zero. The big wins appear when incomes are lopsided: one high earner and one partner on a low income, working part time, caring for children, or out of paid work for part of the year. A useful rule of thumb is that the maximum possible saving is the lower earner’s shortfall against €35,000, taxed at the 20 point gap between the rates.
How to actually elect joint assessment
Joint assessment is the default Revenue applies once a marriage or civil partnership is registered, but it does not happen automatically the year you marry. In the year of marriage you are each still taxed as single people, with a possible refund afterwards if joint treatment would have been kinder. From the following year you can nominate an assessable spouse and elect joint assessment through myAccount, ideally before the end of March so it applies for that tax year. One practical tip: revisit the election whenever incomes change sharply, for example when one partner stops work to care for a child, because that is precisely when the transferable band starts to pay off. Note this calculator assumes both spouses are PAYE employees, so each carries the employee tax credit.
Can both spouses use the full €35,000 transfer at once?
No. The transfer only runs one way, from the lower earner to the higher earner, and it is capped at the lower of €35,000 or the lower earner’s actual income. In our example the lower earner’s €20,000 is well below the €35,000 cap, so all €20,000 of their unused band lifts the higher earner’s cut-off to €73,000, and nothing is wasted.
Does joint assessment affect our USC?
It does not. USC is always calculated individually on each person’s income, so marrying or electing joint assessment leaves your USC untouched. The same is true of PRSI. Only the income tax standard rate band and the way credits are pooled respond to the election.