How does changing the supplier VAT type work? Examples:
(Netherlands) Supplier code: (1) - allows the VAT state/type to be changed.
(USA) Supplier code: (2) - This allows the VAT state/type to be changed even though it has a transaction history.
(USA) Supplier code: (3) - has transaction history, is set as a "Non-EU State", and is set as USD (including the "any currency" option being enabled), however does not allow for the VAT state/type to be changed.
This issue seems to be not related to changing a country's tax status, rather changing the tax status of a supplier.
When you edit a supplier, various checks are made to see what can be changed, and a status is set as follows, in this order:
2 = There are batched transactions
1 = Only fully posted transactions
3 = No transactions, but the supplier has been used in a Stock Price Line record, or is a partnership with attached subcontractors
4 = Selected as a Contra Supplier
5 = There are documents linked to the supplier in the Dimensions database
0 = None of the above.
The VAT type/state can usually can only be changed if the status of the record is not 0 or 3, and the supplier is EU or Non-EU, you can check the tax status of their country record.
The tax status may be changed between EU and Non-EU, but not to Home VAT if:
the country is non-EU and the supplier tax status is EU
The country is EU and the supplier is Non-EU
An explanation using the examples given above:
This is what you see on supplier (2), however the country code on this USA supplier would somehow be set differently, for example MT (and so would see Non-EU State MT in red), which is incorrect.
Because of this, when you edit, we have a Non-EU supplier with an EU country, so the software lets you change between EU and Non-EU.
The USA supplier (3) setup may be incomplete. For example, this may show as a Non-EU State with no country code set, hence does not allow it to be changed.
Similarly supplier (1) is a Netherlands supplier, but its tax status may be set as Non-EU with no country set, but does allow it to be changed in line with the above statuses.
Note: The checks that are made in the software relate to the Countries, not the Currencies.
In Summary, you would need to ensure that the supplier record is correctly setup with the appropriate country in order to allow the VAT Type/State to be correctly set to match, in line with the above status possibilities of the record.