Tax rules 2026

Rule id box1_brackets

Stored value [{"upper": 38883, "rate": 0.3575}, {"upper": 78426, "rate": 0.3756}, {"upper": null, "rate": 0.495}]

Bracket 1 rate = 8.10% income tax + 27.65% national insurance (per bd_box1).

Rule id box1_brackets_aow_born_1946_or_later

Stored value [{"upper": 38883, "rate": 0.1785}, {"upper": 78426, "rate": 0.3756}, {"upper": null, "rate": 0.495}]

Out of v1 calculator scope; recorded for completeness. Born before 1946 and transition-year tables exist on the same page, not recorded.

Rule id algemene_heffingskorting

Stored value {"max": 3115, "phaseout_start": 29736, "phaseout_rate": 0.06398, "zero_from": 78427}

Continuity check passes (3115 - 6.398% x 48690 = ~0 at 78426). Page says rounding can differ by a few euros from the assessment. AOW-age variant: max 1556, rate 0.03195 (not in v1 scope).

Rule id arbeidskorting

Stored value [{"from": 0, "to": 11965, "base": 0, "rate": 0.08324, "over": 0}, {"from": 11966, "to": 25845, "base": 996, "rate": 0.31009, "over": 11965}, {"from": 25846, "to": 45592, "base": 5300, "rate": 0.0195, "over": 25845}, {"from": 45593, "to": 132920, "base": 5685, "rate": -0.0651, "over": 45592}, {"from": 132921, "to": null, "base": 0, "rate": 0, "over": 0}]

Page prints band 3 rate as "1.950%" (likely typo for 1,950%). 1.95% confirmed by continuity: 5300 + 0.0195 x 19747 = 5685. Logged in conflicts.md. Second-source cross-check (loonheffingen PDF) blocked by robots.txt.

Rule id zelfstandigenaftrek

Stored value {"amount": 1200, "amount_aow": 600}

Capped at profit before ondernemersaftrek unless startersaftrek applies. Unused amount carries forward up to 9 years (bd_zelfst_2026). Tax benefit limited to 37.56% rate (bd_zelfst_2026).

Rule id startersaftrek

Stored value {"amount": 2123, "amount_aow": 1062}

AT RISK - Belastingplan 2027 bill art. LXIII(1)(a) makes the cut to EUR 10 retroactive to 2026-01-01 (verified wording). KVK and factsheet say 2027. See conflicts.md C1.

Rule id urencriterium

Stored value {"hours": 1225, "reduced_hours": 800}

Not pro-rated for part-year. 800-hour variant only for startersaftrek bij arbeidsongeschiktheid (out of scope).

Rule id mkb_winstvrijstelling

Stored value {"rate": 0.127}

Also reduces a loss.

Rule id zvw_bijdrage

Stored value {"rate": 0.0485, "max_income": 79409}

Rule id btw_tarieven

Stored value {"standard": 0.21, "reduced": 0.09}

Only KVK read so far; Belastingdienst cross-check pending.

Rule id kor

Stored value {"turnover_max": 20000}

Limit applies to year of registration and the year before.

Rule id arbeidsinkomen_definition

Stored value profit before ondernemersaftrek and mkb-winstvrijstelling

Rule id heffingskortingen_payout

Stored value not paid out, except partner conditions in 21.8.1 (out of v1 scope)

v1 caps total credits at box 1 tax + premiums due. Split 8.10 / 27.65 (21.9.1) not modeled.

Rule id tariefsaanpassing

Stored value {"rate": 0.1194, "threshold": 78426, "max_benefit_rate": 0.3756}

Applies when "inkomen uit werk en woning zonder uw aftrekposten" > 78426. Base: see tariefsaanpassing_basis.

Rule id zvw_basis

Stored value profit minus ondernemersaftrek minus mkb-winstvrijstelling (belastbare winst), at least 0

Resolves A1. KVK example: winst 30.000, zelfstandigenaftrek 1.200, mkb-winstvrijstelling 3.658, belastbaar inkomen 25.142, bijdrage Zvw 4,85% = 1.219. KVK starters page: "Je betaalt deze bijdrage over je winst na aftrekposten." Belastingdienst (fisin 28.2.3, bd_zvw_ondernemer) says only "winst (uit onderneming)", consistent but not explicit. Law confirms (read 2026-10-18 from official BWB XML): Zvw art. 43 lid 2 onder b, bijdrage-inkomen includes "belastbare winst uit onderneming, bepaald volgens de regels van afdeling 3.2 van de Wet inkomstenbelasting 2001"; lid 3 "ten minste op nihil" and capped. Wet IB art. 3.2: belastbare winst = winst "verminderd met de ondernemersaftrek ... en de MKB-winstvrijstelling".

Rule id tariefsaanpassing_basis

Stored value extra tax = rate x min(ondernemersaftrek + mkb_vrijstelling, profit - threshold), only when profit (income before these deductions) > threshold

bd_tariefsaanpassing (2026): "over al uw aftrekposten in de hoogste belastingschijf maximaal 37,56% belasting terug"; zelfstandigenaftrek and mkb-winstvrijstelling listed. bd_fisin_ch29 29.2.1: test is box 1 income "zonder uw aftrekposten" > 78.426. kst_33756_3 (MvT Belastingplan 2014, eigen woning only) voorbeelden 2 and 3: the correction covers only the part of the deductions taken against the top bracket. Extension of the same mechanism to ondernemersfaciliteiten taken from bd_tariefsaanpassing. Law confirms (Wet IB art. 2.10 lid 2, version 2026-01-01): table amount "vermeerderd met 11,94% van het bedrag waarmee de som van het belastbare inkomen uit werk en woning en de in aftrek gebrachte bedragen ... [EUR 78.426] te boven gaat, doch ten hoogste met 11,94% van de in aftrek gebrachte bedragen"; lid 3 lists ondernemersaftrek and MKB-winstvrijstelling.

Rule id afschrijving_drempel

Stored value {"amount": 450}

bd_afschrijven: "Koopt u een bedrijfsmiddel voor minder dan EUR 450? Dan trekt u het bedrag wel in 1 keer af als kosten." bd_kosten_1_jaar: "Als regel kunt u aanhouden dat dit zaken zijn met een kostprijs van minder dan EUR 450", excl. VAT if VAT is reclaimable, else incl. VAT. Pages are not year-specific; read for 2026.