# Money and branded values [#money-and-branded-values]

TaxKit uses branded and schema-backed values for tax-significant data. Money
uses integer cents and a currency, not floating-point dollars.

## When this matters [#when-this-matters]

Use checked cents when building SDK input. Send tagged JSON values when
calling HTTP. The same Money schema owns both forms.

## How it works [#how-it-works]

```ts
import { Cents, aud } from "@taxkit/core/primitives";

const taxableIncome = aud(Cents.make(9_000_000));
```

Use `Cents.make` for known constants. `aud` takes checked cents and returns a
Money value directly. Fractional cents and numbers outside JavaScript's safe
integer range are unsupported.

The matching HTTP JSON is:

```json
{ "_tag": "Money", "cents": 9000000, "currency": "AUD" }
```

## Check a number or a calculated amount [#check-a-number-or-a-calculated-amount]

Use `audFromCents` when a number needs checking. It returns an Effect that
produces Money or `InvalidMoneyValue`. `audDollars` uses the same check after
rounding dollars to cents. Your application host runs the Effect.

```ts
import { audFromCents, moneyAdd } from "@taxkit/core/primitives";
import { Effect } from "effect";

const amountProgram = Effect.gen(function* () {
  const amount = yield* audFromCents(9_000_000);
  const extra = yield* audFromCents(100);
  return yield* moneyAdd(amount, extra);
});
```

Addition, subtraction, money rounding and ledger totals return checked failures
when a result is too large. You can handle `InvalidMoneyValue` through the
Effect error channel. For JSON or other unknown input, decode the owning
schema at your application boundary; do not cast the input to Money.

`CalculatorId`, `Jurisdiction` and `TaxYear` are also branded or literal
boundary values owned by packages. Use exported values and schemas instead of
duplicating string fields in reusable code.

## Related concepts [#related-concepts]

* [Facts](/concepts/facts)
* [Type safety](/sdk/type-safety)
* [Facts architecture](https://github.com/crcorbett/taxkit/blob/a151e51e8a30247526fa93412df046955846eca4/docs/architecture/facts.md)