Requirements

From composer.json:

PHP ^8.4
ext-dom — XML parsing for tax-ID validation.
ext-zlib — the register is served gzipped (1.8 MB against 54 MB of JSON) and inflated on read.
cboxdk/tax-resolver ^1.1 — the shared address-to-jurisdiction resolver. The register runs the SAME code over its own artifacts at build time, which is the only thing that keeps two readers of one format from drifting apart.
Laravel ^13 (illuminate/contracts, illuminate/support, illuminate/http)
cboxdk/laravel-geo ^0.6 — the canonical jurisdiction reference every assessment binds to.
brick/money ^0.14 || ^0.15 — exact integer-minor-unit money for amounts and rate maths.

No database migration is required. The default TaxRateSource reads a local register compiled by php artisan tax:data:sync; a fresh install refuses until that data is available. See The register.

Why Laravel 13 only

A library should install on the current and previous Laravel major, and this one does not. The cause is external and it is not a constraint this package can widen its way out of:

brick/money — the exact-money library every amount and rate calculation runs through — has required brick/math ~0.15 or newer since its 0.12 release.
Every laravel/framework 12 release requires brick/math and caps it below that: ^0.11|^0.12 at v12.0.0, ^0.11|^0.12|^0.13|^0.14 in the current patches.

The ranges are disjoint, so an application on Laravel 12 cannot install a current brick/money at all — with or without this package. Widening illuminate/* to ^12.0 || ^13.0 here would not change that: the subsplits (illuminate/support, illuminate/contracts, illuminate/http) do not require brick/math themselves, so this package would merely resolve against Laravel 12 in isolation and then fail in any real application, which is a worse failure than an honest constraint.

The alternative is pinning brick/money back to ^0.11, the newest release that accepts brick/math ~0.14. For a tax engine the money library's behaviour is the calculation — rounding, allocation, minor units — so trading three minors of it for reach on a superseded framework major is the wrong way round.

This widens the day Laravel 12 accepts brick/math ~0.15, which a stable major is unlikely to do, or the day Laravel 12 stops being the previous major.