Tax identification number (TIN) – is a unique number which helps identify the taxpayer, issued upon registration with the tax authority in the country where you are a taxpayer.
The tax identification number remains permanently valid and does not change, for example after a move, a change of name, or a change of civil status.
In different countries, there might be a different term for that, but in essence, this is always just the taxpayer ID in your country.
You can find your tax identification number for the following countries in the links below:
For other countries, the tax identification number might be found in tax documents or on your country's tax administration portal. Further information on tax identification numbers in the European Union can be found here.