Facts

Facts are schema-backed values with stable identities. They are not arbitrary request fields.

When this matters

You work with facts when you build calculator input, show calculator help or review why a value was accepted or rejected. A structurally similar object is not the same fact unless it matches the owning schema.

How it works

ts
import { Cents, aud } from "@taxkit/core/primitives";
import { GrossPay } from "@taxkit/rules-au-pay";

const grossPay = new GrossPay({
  amount: aud(Cents.make(165_400)),
  period: "weekly",
});

The GrossPay tag and Money value are part of the boundary. HTTP callers send the tagged JSON form; SDK callers use the constructors.

Fact authority

Input facts are supplied by the caller. Derived facts are produced by rules. Parameter facts and services provide tax-year tables, rates and constants.

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