Currently both resident and non-resident businesses operating in Bulgaria must register for VAT once they exceed BGN 50,000 (£22,000) in taxable supplies within a year.
However the recent amendments, which are set to be implemented as of January 1st 2020, will see non-resident taxpayers be obliged to register for VAT as soon as they make their first taxable supply to Bulgaria.
Source: vatglobal.com