Project · NL zzp tax calculator · live

De Munt

Full BTW and IB/Zvw math in the browser – nothing is sent anywhere, no signup.

Freelancing in the Netherlands means the same arithmetic every quarter: which BTW box each invoice belongs to, what is left after voorbelasting, how much income tax and Zvw premium is coming, what to set aside this month so the bill in spring is not a surprise. I went looking for something that would just do it – everything was either paid, or built for accountants, or last updated years ago.

So I sat down and worked the rules out properly: the BTW boxes 1a, 1b, 3a, 3b, 5b sorted by rate, the EU B2B reverse-charge case, the IB brackets with startersaftrek, the Zvw premium, the monthly reserve. It runs entirely in the browser – no account, no server, nothing about your income leaves your machine.

Built it for my own quarter, then put it online because everyone I knew was redoing the same spreadsheet. The bigger suite around it – invoices, quotes, ledger – is what I am building next.

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