The 2026 rate cap turns a private deduction into a business-owner liquidity question.
A founder at the kitchen table can see the problem in one minute. The business account looks steady. VAT is reserved. A supplier needs paying on Friday. Then the private mortgage calculation arrives. It is no longer only a family item. It is part of cash planning.
Cash pressure comes first
Belastingdienst keeps the 2026 rule clear. Taxpayers with income from work and home before deductions above €78,426 receive less deduction for own-home interest and costs. The maximum deduction rate in the high bracket is 37.56%. The correction is 11.94%.
Where the tax line actually sits
Article 2.10 of the Wet inkomstenbelasting 2001 sets the 2026 second box 1 rate at 37.56% and the top rate at 49.50%. The correction is the difference between those rates. In plain language, a taxpayer in the highest bracket does not get the full value of the deduction at the top income-tax rate.
Belastingdienst also says the return and the assessment calculate the correction automatically. That helps. It cuts arithmetic mistakes. It does not settle the cash effect in advance. A return can be correct while the household plan is already off.
Credit still sets the limit
The rule is wider than mortgage interest. Belastingdienst applies the same rate limit to the ondernemersaftrek, the MKB-winstvrijstelling, the terbeschikkingstellingsvrijstelling and persoonsgebonden aftrek. Deductible own-home costs can also include periodic erfpacht payments and certain mortgage financing costs.
Why the private house enters the business conversation
I read this as a boundary problem. The mortgage is private, but the income that changes the deduction often comes from the business. For a ZZP worker, a strong year can push box 1 income over the threshold. For an owner-manager, salary and household cash sit beside dividend expectations, bank covenants and company liquidity.
That does not turn the house into a business asset. It means weak boundaries can let private pressure reach the company. The founder at the kitchen table may take extra drawings after a good month, while the provisional assessment still reflects older mortgage interest, lower income or a softer year.
Rijksoverheid adds another pressure point. In 2026, the usual inflation correction in income tax was not fully applied. The upper limit of the second bracket moves to €78,426. Full indexation would have taken it higher. For a business owner with uneven profit, that shift matters. It changes the point where the correction starts to bite.
Housing pressure makes tax comfort unreliable
The housing market keeps the issue alive. CBS and Kadaster reported on 22 June that existing owner-occupied homes were 4.4% more expensive in May 2026 than a year earlier. In the first five months of 2026, 94,523 homes were sold, 5% more than in the same period a year earlier. The market is not in panic. It is still expensive.
What small firms should separate
DNB gives the scale. Dutch households had more than €890 billion in mortgage debt with Dutch financial institutions at the end of 2025. DNB and AFM also reported that since mid-2023 house prices rose by 21%, while incomes rose by 14%. More than half of starters have a mortgage above 90% of the home value, and starters use on average 92% of their borrowing capacity.
That is why I would not treat tax relief as repayment strength. A deduction can ease the tax bill, but it does not pay the bank by itself. Interest, income volatility, private spending, company cash and the provisional assessment all meet on the same bank statement.
The review that matters
The useful discipline is simple, but it needs real figures. A founder’s 2026 review should put expected box 1 income before deductions, deductible own-home costs and the current provisional assessment in one conversation. For a sole trader, entrepreneur deductions and the MKB-winstvrijstelling belong there too, because the rate limitation reaches both.
Buyers need a separate check. Rijksoverheid sets the starter transfer-tax exemption at homes up to €555,000 for buyers aged 18 to 35. The transfer-tax rate for homes not occupied by the buyer drops to 8.0%. Those switches are separate. They do not belong in the same basket as the mortgage interest deduction.
The founder at the kitchen table does not need drama. She needs the private mortgage calculation to stop drifting beside the company ledger as if it were unrelated. The tax system will do its arithmetic. The owner still has to protect the boundary between household pressure and business cash. That is where the discipline sits.
Sources
- Beantwoording Kamervragen niet verruimen hypotheekrenteaftrek – Taxence
- Belastingdienst – 2026 mortgage interest deduction rate cap
- Wettenbank – Legal mechanism for the rate cap on ground-reducing deductions
- Rijksoverheid, Ministry of Finance – Policy and implementation limits on linking the deduction to the first bracket
- Rijksoverheid, Ministry of Finance – 2025 follow-up questions on the joint basic income-tax rate
- Rijksoverheid – Belastingplan 2026 income-tax bracket context
- Rijksoverheid – Other 2026 own-home tax changes
- Rijksoverheid, Ministry of Housing and Spatial Planning budget 2026 – Budgetary weight of the mortgage interest deduction
Referenced in the article
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