In 2024, tax software ought not to have the tax rules hardcoded, but instead ask the tax authority for a fresh set of rules at startup every time, and alert the user if the rules database ever gets more than 30 days out of date.
Nearly every government makes tax rule changes every year - it just isn't reasonable to hardcode them and require the user buy/install new software every year.
The changes go beyond tax band thresholds and percentages across NIC & IT. Eg the (now-scrapped) Health & Social Care Levy would've been a completely new tax - you need a complex schema to encode that and even then the Treasury will come up with something you haven't thought of next.
Tax rules are very complicated and often can't just be expressed as an entry in a database. In that context, downloading a fresh set of rules at startup is effectively the same as auto-updating.