How we calculate

The rules behind every result on this site, and how we keep them current.

Rates come from official sources

We take rates from Revenue, the Department of Finance Budget documents, the Department of Social Protection, the Central Bank of Ireland and gov.ie. Where an official page could not be read, we cross-check against at least one tax adviser's published tables and note it on rates and sources.

Every rate has a date

Each rate is stored with the date it starts and ends. That lets one calculator handle changes in the middle of a year. For example, employee PRSI rose from 4.2% to 4.35% on 1 October 2026, so a 2026 salary pays 39 weeks at the old rate and 13 weeks at the new one. Capital gains tax and gift and inheritance tax changed on 7 October 2026, so those calculators ask for the date of the sale or gift.

Announced is not the same as law

A Budget announces changes in October. They become law when the Finance Act is signed, usually in December. Until then, we label the new figures as announced. They can still change, though they rarely do.

Every calculation is tested

Each calculator is checked against worked examples: published Revenue examples, band edges such as stamp duty at exactly €1 million, and figures worked out by hand. The tests run before every update goes live.

When we check

• Budget day each October, and again when the Finance Bill is published.
• When the Finance Act is signed in December.
• At the start of each year, when welfare rates and the minimum wage change.
• On any date a rate is scheduled to change, such as PRSI each October.

Limits

Results are estimates. They cover the common cases and each page says what it leaves out. They are not tax returns and not financial advice.