Greek VAT says it's invalid
I recently received an email that asks me to enter my VAT.
When I do enter it, it says it's invalid - I've tried both WITH and WITHOUT the country code prefix (GR) and in both cases it says
This VAT number is invalid.
even-though I know this is my real vat.
I don't own a company, I just rent my private property as an individual and I'm not sure what to do.