The situation
- Fiscal partners filing jointly.
- Partner 1 earns €62,000; partner 2 earns €34,000.
- Own home with WOZ value €450,000; mortgage interest €900 a month, all deducted by partner 1.
- Joint savings €60,000.
The home
- Eigenwoningforfait (0.35% of €450,000)
- + €1,575
- Mortgage interest (12 × €900)
- − €10,800
- Net deduction for partner 1
- − €9,225
Box 1 per partner
- Partner 1 taxable income
- €52,775
- Partner 1 tax after credits
- €12,861
- Partner 2 taxable income
- €34,000
- Partner 2 tax after credits
- €3,854
Partner 2 pays much less because the tax credits are worth relatively more at a lower income.
Box 3 and total
Their €60,000 of savings is below the joint tax-free allowance of €118,714, so there is no Box 3 tax. Total income tax for 2026 is €16,714.
With a provisional assessment, the mortgage deduction comes back as a monthly refund instead of once a year. Compare filing options in the full calculator.
Sources
This article is based on these official pages. If anything here differs from them, the official page is right.
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