Currently your regex for Belgium checks for BE + optional zero + 9 digits.
Belgium has ran out of VAT numbers in the BE0 range since end of year 2022 and has officially been using BE1 + 9 digit range since 1-jan-2023, so for almost two years now.
Your regex does not allow for BE1 range VAT numbers.
(and so do many many many other example codes online, but yours is one of the first to pop up)
i'm not as involved with vat number validation in a work capacity anymore, but i'd be happy to help if you could send over a few valid vat numbers that i can test with.
Currently your regex for Belgium checks for BE + optional zero + 9 digits. Belgium has ran out of VAT numbers in the BE0 range since end of year 2022 and has officially been using BE1 + 9 digit range since 1-jan-2023, so for almost two years now.
Your regex does not allow for BE1 range VAT numbers. (and so do many many many other example codes online, but yours is one of the first to pop up)