Calculators
CalcuIVA
VAT calculator: add or remove 21%, 10% or 4% from any amount and see which part is yours and which part you're holding for the tax office.
The brief
The most repeated operation on any invoice: adding or removing VAT. It sounds trivial, which is exactly why almost nobody checks it.
The problem
There’s a widespread mistake: to remove VAT you divide, you don’t subtract the percentage. Taking 21% off €121 gives €95.59, when the real base is €100. That error slips into quotes and invoices every day.
There’s a second confusion too: the VAT you charge isn’t yours. It’s money you’re holding until you settle up.
The solution
A calculator that works both ways — adding and removing — with the three current rates plus a custom option. It shows the taxable base, the tax due and the total, and splits the amount visually: how much is yours and how much belongs to the tax office.
It also shows the same amount under the other rates for quick comparison, and explains which rate applies to which kind of product. Every result can be expanded to reveal the arithmetic, which is what stops the mistake from repeating.
Calculation runs in the browser, with no sign-up and an option to print or save as PDF.
Outcome
Live at calcuiva.com with the rates in force for 2026.
