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Tax guide

Know the dates. Know the words.

The dates, words and letters every newcomer meets in the Dutch tax system.

123 Tax › Tax guide · Last checked: 26 October 2026

Key dates

1 March

You can file the normal tax return for last year.

1 May

Deadline for the normal tax return – or ask for an extension.

1 May – 1 July

The M form for 2025 could be filed in this period in 2026.

1 September

Last day to apply for last year’s allowances.

Dutch tax words

Aangifte

Tax return.

Aanslag

Assessment – the tax office’s decision on what you pay or get back.

Voorlopige aanslag

Provisional assessment – an advance, often paid monthly.

Jaaropgaaf

Annual salary statement from your employer.

Heffingskorting

Tax credit that lowers the tax you pay.

Bezwaar

Objection – within 6 weeks after a decision.

Machtiging

Authorisation to let someone file for you.

Toeslagpartner

The partner whose income counts for allowances.

Letters and scams

Blue envelope

Real letters from the Belastingdienst come in a blue envelope or in your Berichtenbox.

No links by SMS

The tax office does not send payment links by SMS or WhatsApp.

Pay the right account

Pay only to the account on the assessment itself.

Report it

Report suspicious messages to the Fraud Helpdesk.

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General information about Dutch tax for 2026, not personal tax advice. Rules and amounts change every year – we check your own situation before we file anything. 123 Tax is not part of the Dutch Tax Administration (Belastingdienst).