Money
Tax rates
Rates are data with a scope and a date, resolution is most-specific-wins, and a rate scoped elsewhere is never a fallback.
A rate of tax is a row, not a branch on a country code. It carries a name, a rate in basis points, where it applies, and the dates between which it applied. Georgian VAT at 18%, a UAE 5%, a zero-rated export, a reverse charge — all the same shape.
Scope and resolution
Rates resolve most-specific-wins: a rate scoped to a country and a region beats one scoped to the country, which beats one scoped to nothing. It is the same rule leave policy and jurisdiction use, and deliberately so — one rule to learn.
A rate scoped somewhere else is never used as a fallback
A Georgian rate is not a worse-but-usable answer for a UAE invoice; it is the wrong answer. Where nothing matches, nothing is suggested, and the line is left for a person to fill in. Silence is the honest answer, and a plausible wrong rate is the one that gets signed off.
Dates
A rate has a date it took effect and, once it stops applying, a date it stopped. A rate that changes is a new row and the old one is closed — never an edit, because an invoice issued last year was correct at the rate then in force and must still say so.
Which rates are offered on a line is resolved from the issuing entity's own country and as of the document's own issue date — it is your VAT regime you charge under, and back-dating a document offers the rates that were current then. Where nothing applies the editor says so and links to the settings, rather than presenting an empty list that reads as a fault.
Resolution decides what can be chosen, never what already was
A draft that already names a rate keeps it in the picker even if that rate has since been closed or moved to another country. Dropping it would show the line as untaxed while the stored value said otherwise.
Reverse charge
A reverse-charge rate charges nothing and says why on the document. The net still counts toward the turnover figures — it is not zero-rated and it is not exempt, and collapsing the three is how a return comes to understate what it was supposed to declare.
Treatment is suggested, never decided
Where a customer is business-registered in another EU member state, the reverse charge is offered with the reason attached. It is offered because the facts fit a common case, not because the product has concluded anything about your obligations — and it is a suggestion on a draft, which somebody accepts or ignores.
Editing and deleting
A rate that has been used on a document cannot be deleted. That link is how somebody later answers what was charged and under which rule; without it, an old invoice's tax line is a number with no explanation. Deactivate it instead — it stops being offered and existing documents keep meaning what they meant.