Dutch Box 3 Wealth Tax Calculator | Deemed Return 2026

You are taxed on returns the state assumes you made

Box 3's transitional system does not ask what your portfolio actually earned. It assigns each asset class a DEEMED yield, 1.03% for bank savings, 6.00% for investments and other assets, minus 2.46% on debts in 2026, and taxes 36% of that fiction. A stock portfolio that lost 10% last year is taxed exactly like one that gained 20%, because the Belastingdienst's spreadsheet says both earned 6.00%.

That asymmetry is why the 2021 Supreme Court's Kerstarrest ruling forced the whole rebuild, and why the tegenbewijsregeling exists in the meantime: if you can show your ACTUAL return across all Box 3 assets was lower than the deemed calculation, you may be taxed on the real figure instead. For anyone whose investments had a bad year, filing that counter-evidence statement is not optional homework, it is the difference between taxing a gain that never happened and not.

2028 changes the question from 'what do you own' to 'what did it earn'

The Wet werkelijk rendement box 3, planned for 2028, taxes actual returns: interest, dividends, and, for liquid assets like shares and crypto, UNREALISED annual gains under a vermogensaanwasbelasting. Paper gains become taxable the year they appear, whether or not you sell; real estate stays on a realisation basis, taxed when sold.

The allowance structure flips with it: today's €59,357 tax-free CAPITAL per person becomes a €1,800 tax-free RESULT. Small savers stay effectively untaxed either way, but large portfolios in good years pay far more under 2028 rules, and the same portfolio in a loss year pays nothing and banks a carry-forward. The calculator's side-by-side view exists precisely because the two systems rank portfolios differently: heavy cash favours today's rules; volatile equities favour whichever year you are actually in.

The unglamorous preparation that matters: cost-basis records. From 2028 the tax follows year-on-year value changes, and taxpayers who cannot document purchase prices hand the Belastingdienst permission to estimate conservatively. Start the spreadsheet now, two years of history at the switch is worth real money.

The moves that still work, and the ones that stopped working

Fiscal partners can allocate Box 3 wealth between them freely on the return, doubling the €59,357 allowance to €118,714 and, from 2028, doubling the €1,800 result threshold. Failing to optimise that allocation is the most common leak in Dutch returns, it costs nothing to fix and the software does it in one checkbox.

The reference date remains 1 January, which historically invited peildatumarbitrage, briefly converting investments to savings around New Year to catch the lower deemed rate. Anti-arbitrage rules now look through conversions inside a three-month window around the date, so the seasonal shuffle is closed; genuine, durable allocation changes still count.

Two classification points save more than any trick: your primary home is Box 1, not Box 3, so it never enters this calculator; and foreign property generally gets double-tax relief when the host country already taxes it, reported in Box 3 but largely neutralised. Getting either wrong overstates the bill by thousands.