Updated
How IrishNetPay.com calculates your Irish take-home pay
The order in which the calculation runs
A payslip is not a single percentage. Three separate charges are worked out on your gross pay, each with its own rules, and the calculator applies them in the order Revenue uses.
First, PAYE. Income up to your standard rate cut-off point is charged at 20 %, the balance at 40 %. The cut-off depends on your marital status and, for married couples, on whether both spouses work. The gross tax is then reduced by your tax credits, the personal credit and the employee (PAYE) credit for most people. Credits reduce the tax itself, not the income, which is why they are subtracted last.
Second, USC, the Universal Social Charge. It is charged on gross income with no credits, through its own set of bands, and it starts only once income passes the annual exemption threshold. Someone below that threshold pays no USC at all, which is why very low salaries show a different effective rate from what a flat percentage would suggest.
Third, PRSI, calculated at Class A1 for standard employees. A weekly credit tapers the charge for lower earnings rather than switching it on abruptly, so the calculator computes PRSI on a weekly basis and annualises the result instead of applying a single annual rate.
Why the annual figure and twelve monthly figures do not always match
PAYE and USC are cumulative over the tax year, while PRSI is assessed per pay period. Dividing an annual result by twelve is therefore an approximation, and a real payslip can differ by a few euro in any given month, particularly in January and after a pay rise.
The calculator shows the annual position, which is the one that settles at year end, and derives the monthly and weekly views from it. Where an employer operates a Week 1 basis, the real deductions will differ until the cumulative basis resumes.
What the calculator does not do
It does not model benefit-in-kind, share schemes, pension relief at source, the Small Benefit Exemption, rent tax credit or any other credit you claim individually. It assumes a single employment with a standard tax credit certificate.
It is an estimate for guidance. Your actual liability is determined by Revenue on the basis of your own certificate and circumstances, and a payroll department applies rules the calculator cannot see.
When the figures are updated
Rates, bands, credits and thresholds are revised each year in the Budget and take effect on 1 January. We update the calculator once the Finance Act figures are published, not on the strength of Budget-night reporting, because the published figures occasionally differ from what is announced.
Every page carries the date of its last revision at the top and in the footer. That date comes from the site's version history, so it reflects a real change to the page rather than an automatic refresh.
Where the figures come from
Every rate and threshold used by the calculator is taken from the following official publications, and nothing is derived from third-party summaries: