Reverse VAT Calculator

Reverse VAT: divide, never subtract

A reverse VAT calculation starts from a price that already contains the tax and works back to the figures underneath. One rule governs the whole page: to remove VAT you divide by one plus the rate. At 23%, divide by 1.23. At 13.5%, divide by 1.135. At 9%, divide by 1.09.

A €123 purchase at the standard rate holds a net of 123 / 1.23 = €100 and €23 of VAT. Subtracting 23% from €123 gives €94.71, which is wrong by more than five euro, because the 23% was charged on the smaller net figure, not on the gross you are holding. Subtraction overshoots on every reverse calculation at every rate, and the error grows with the rate. The calculator applies the division for you at any Irish rate or a custom one, and shows the same gross stripped at all five Irish rates side by side.

The VAT fractions, for checking by hand

Accountants use a shortcut worth stealing: the VAT fraction, which takes you from gross straight to the VAT without computing the net first. At 23% the fraction is 23/123. Multiply any gross by it and the VAT drops out: 123 x 23/123 = 23. The fractions for the Irish rates:

The middle column explains a number that surprises people: a 23% rate means VAT is 18.7% of the gross. Anyone who estimates the VAT in a receipt by taking 23% of the total overstates it by nearly a quarter.

Working back from the VAT amount alone

Sometimes the VAT figure is the only number you trust: a VAT3 box, a credit note, a supplier statement showing tax but not the breakdown. Divide the VAT by the rate itself and the net reappears.

€46 of VAT at 23% points to a net of 46 / 0.23 = €200 and a gross of €246. Bookkeepers use this direction constantly to test whether a claimed input figure on a VAT3 return squares with the purchase it supposedly came from. The second tab runs it at whichever rate you select.

The rate checker: auditing an invoice in five seconds

Given a net and a gross, the rate the supplier actually applied is a one-line calculation, and comparing it against the Irish rates catches real errors. The classic finds: a builder invoicing at 23% where construction services carry 13.5%, a caterer still charging 13.5% on food after the 1 July 2026 move to 9%, or an invoice whose implied rate matches nothing because someone fat-fingered a line. Overcharged VAT is not free money for the supplier and not reclaimable in full comfort for you; the clean fix is a corrected invoice, and the checker gives you the evidence to ask for one.

Mixed-rate receipts: the splitter

Since 1 July 2026 the ordinary restaurant bill carries two rates: the food at 9%, the wine and soft drinks at 23%. Supermarket receipts have mixed zero-rated groceries with standard-rated household goods for decades. The receipt splitter takes each line at its own rate and produces per-rate subtotals plus the overall net, VAT and gross, which is the exact shape expense software and the RTD want the numbers in. One caution belongs here: reclaiming input VAT requires a proper VAT invoice, and business entertainment is excluded from deduction regardless of the receipt. The splitter tells you what VAT a bill contains; whether that VAT is reclaimable is a rules question, and our VAT guide covers where the lines sit.

Where reverse VAT shows up in practice

Quoting jobs: a customer names the total they will pay, and you need the net that fits under it before costing the work. Pricing decisions: a shelf price is fixed by the market, and the margin conversation starts from the net underneath it, which is why the margin calculator and this page are used together. Expense claims, mileage-and-subsistence audits, insurance settlements quoted gross, and second-hand deals under the margin scheme, where the VAT is extracted from within the margin by exactly the division this page performs. The forward direction, adding VAT to a net price, lives on the main VAT Calculator Ireland along with the invoice mode; everything that runs the other way lives here.