Netherlands ZZP/Eenmanszaak — IB-aangifte, BTW-aangifte & ZVW

Establish that the client is a full-year Netherlands resident operating as a ZZP'er / eenmanszaak (not a BV or VOF). Confirm KvK registration, BTW registration type (regular quarterly filer vs KOR kleineondernemersregeling under EUR 20,000 threshold), and whether any employment income (jaaropgave) or Box 3 wealth exists. Part-year residents trigger the M-biljet route and must be referred to a belastingadviseur.

Client uploads all source documents in one batch: business bank statements (ING Zakelijk, Rabobank, ABN AMRO, Bunq CSV/PDF), sales invoices (verkoopfacturen), purchase invoices/receipts (inkoopfacturen), prior quarterly BTW-aangiften, any jaaropgave from employment, voorlopige aanslag notices, and WOZ-beschikking plus mortgage statement if an eigen woning deduction applies. The agent parses each document, extracts omzet (ex-BTW), bedrijfskosten by category, BTW collected and paid, and flags any Stripe/PayPal/Mollie payouts requiring gross-up.

Verify that the four quarterly BTW-aangiften (rubrieken 1a hoog tarief 21%, 1b laag tarief 9%, 1e 0%/vrijgesteld, rubriek 5b voorbelasting) are complete and that total declared turnover matches the omzet extracted from the bank statements and invoices. If a Q4 aangifte is outstanding or a suppletie is required, draft it. KOR clients file one annual BTW declaration instead. Cross-check that BTW afdracht payments to Belastingdienst are excluded from IB bedrijfskosten.

Compute IB-aangifte Box 1 winst uit onderneming. All amounts are ex-BTW. Apply the ondernemersaftrek chain: (1) gross winst minus bedrijfskosten and afschrijvingen; (2) zelfstandigenaftrek EUR 2,470 (2025) — only if urencriterium of 1,225 hours/year is confirmed with an urenstaat; (3) startersaftrek EUR 2,123 additional — only in years 1–3; (4) MKB-winstvrijstelling 12.7% on the result — mandatory for all entrepreneurs regardless of urencriterium. Check KIA (kleinschaligheidsinvesteringsaftrek) if qualifying asset purchases exceed EUR 2,801. Flag schijnzelfstandigheid if a single client exceeds 70% of omzet.

If the client owns their primary residence, compute the eigen woning saldo: add eigenwoningforfait (0.35% of WOZ-waarde for properties EUR 75,000–EUR 1,310,000 in 2025) then subtract hypotheekrenteaftrek (limited to 36.97% rate in 2025). Apply the Hillen-aftrek phase-out (80% in 2025) if the mortgage is largely repaid. Assess Box 3 wealth: if total assets exceed heffingvrij vermogen of EUR 57,000 per person, a Box 3 return is required — flag and escalate if complex. Compute income-dependent heffingskortingen: algemene heffingskorting (up to EUR 3,068, phases out above EUR 24,813) and arbeidskorting (up to EUR 5,174, phases out above EUR 43,071).

Compute the Zorgverzekeringswet (ZVW) income-related health insurance contribution on bijdrage-inkomen (= belastbare winst uit onderneming, capped at EUR 71,628 in 2025). ZZP'ers pay ZVW themselves at 5.32% (2025 rate) — this is separate from and not deductible in Box 1. Reconcile all voorlopige aanslag IB payments made during the year against the computed IB liability to determine the final balance due or refund. Recommend a 2026 voorlopige aanslag adjustment if the client's expected profit differs materially.

Assemble the complete reviewer package: Excel working paper with all Box 1/3 schedules and live formulas, BTW reconciliation, ZVW computation, and voorlopige aanslag reconciliation. Run the cross-skill consistency checks (BTW omzet vs IB omzet must match within EUR 1; ZVW bijdrage-inkomen vs Box 1 belastbare winst; ondernemersaftrek chain order). Produce a belastingadviseur reviewer brief flagging all T2 items (urencriterium evidence, mixed-use expense percentages, werkruimte claim, schijnzelfstandigheid risk, Box 3 composition) and a filing calendar with all deadlines. All outputs must be reviewed and signed off by a qualified belastingadviseur before filing via Mijn Belastingdienst with DigiD.