Layer zero, in both senses.
Underneath everything, and disclosing nothing. Tacit decides the questions Dutch housing law actually asks — whether a household qualifies for a rental home, whether a buyer's declared financing covers a bid — from what each person declares, seals the answer at the source, and issues it on the wallet standard — held on the holder's behalf until a wallet takes it. What sits above it stops rebuilding that logic; what sits below it is already the state's.
Where it sits
The market does not lack attestations — the tax authority already puts income into wallets and identity is solved, so the pieces a landlord's question is made of already exist, separately, in the renter's hands. What it lacks is the layer that turns those into a verdict: qualified for this home, under this regime, signed and portable. Only Tacit issues it, and what the renter then holds is their position in the market rather than a document about them.
Every Member State must make a certified wallet available by the end of 2026 — and the eligibility checks Dutch rental law already requires will then be made against what renters carry.
And the verdict is not the only sealed document. The same rail seals what each party to a transaction declares: an owner's declaration of ownership — the root every Rental and Sale mandate rests on — a renter's self-declaration, a buyer's declaration, the seller's disclosure co-signed by every co-owner, and mandates a counterparty can verify outside the office that holds them. Attesters sign into it too: a mortgage adviser co-signs the buyer's financing statement by passkey, and appraisals and inspections arrive as seals.
A layer that everything runs on does not compete with what runs on it. That the same layer discloses nothing is not a second feature; it is the reason a competitor can rely on it.
Every portal decides eligibility today — privately, unsigned, and again from scratch for each application. So does every CRM, and every office deciding whether a bid is worth taking. A portal that consumes verdicts stops rebuilding that logic and starts publishing a requirement the wallet answers; the answer it gets back is one it can prove it was given.
The law, executable
Two rulebooks: 92 Rental rules and 77 Sale rules, one hundred and sixty-nine in all across thirty-seven policies, each browsable rule by rule with the decision model it runs as. Every rule cites the law or market convention it comes from, and one that cites no source cannot be stored — the database refuses it. Twenty-four governed values are statutory — each carrying its source, its publication date and the quoted text it was read from — and seven more are market convention. The software knows which is which, because a statutory value and a convention do not change for the same reasons.
Rental: which regimes it decides
Stated per regime, because "every segment" would not be true. Eligibility for the free market, for mid-market private lettings and for mid-market corporation stock is decided end to end and opens the catalogue's entry gate, alongside a short-stay pathway. Corporation allocation rules (passend toewijzen) are not encoded; the corporation's own allocation applies. Social housing is governed by its own rules but publishes no income requirement, and that is correct rather than missing: allocation there runs on a statutory household-income ceiling set in law, which is not expressible as a multiple of the rent.
Nineteen yes-or-no answers. No figure exists to leak.
The Rental credential holds predicates, not values — meets the requirement at this rent, never earns this much. Nineteen are disclosable, and the renter chooses which to present, one rental at a time. Two more are provenance claims that can never be hidden: which jurisdiction decided, and which version of the rulebook. An answer without those cannot be judged.
Matching exchanges booleans and nothing else. The income a verdict rests on stays committed inside the credential and is never disclosed — and because the commitment is already sealed into every credential issued, a zero-knowledge range proof can be added as a layer without re-issuing a single one.
How to take it
- Ask for a verdictYour system sends what it holds and receives a governed answer with its reasons. Nothing else in your stack changes.
- Issue to a walletAn OpenID4VCI route issues the credential to a wallet, so it can keep working after they leave your funnel. The route exists; no wallet app has yet been tested against it.
- Verify what others issuedAccept credentials renters already carry — from Tacit, or from any issuer you decide to trust.
What a consumer implements for the first path: an authenticated call to open a session, a call to submit what they already hold, and a call to retrieve the sealed result. An OpenAPI document describes the surface; the wallet and verification paths are further, and are the reason the second and third rows exist.
Sale: statements, never amounts
The Sale rulebook never decides what a buyer may borrow. It departs from the mortgage adviser's statement — co-signed by the adviser, whose firm is checked against its register entry — and answers the question a bid asks: does declared financing cover this amount, yes or no. A buyer's position at a bid is sealed the same way a renter's verdict is.
Around that answer, it states what the law attaches to the purchase rather than computing a figure for anyone: which transfer-tax rate applies and who decides the starter exemption, whether the buyer is entitled to the statutory reflection period, NHG eligibility as advice, the energy label the advert and the award require, and what leasehold, an owners' association or an apartment right means for this home. Once an agreement is signed, it states the clocks: the reflection period's end and each condition's deadline.