This distinction matters if you are moving to Bulgaria for the 10% tax regime.

Residence

Immigration residence answers whether you are legally allowed to live in Bulgaria and under what route.

Tax residence

Tax residence is decided under tax law. It can look at time spent in a country, your home, family, economic ties and other facts.

183 days is not the whole test

Day counts matter, but they are not the only rule. A country can sometimes treat you as tax resident even if you spend fewer than 183 days there.

You also need to leave the old system properly

Moving to Bulgaria does not erase your previous tax residence automatically. The country you leave may still look at your home, family, work and business ties.

Takeaway

Get the immigration route and tax position checked separately, then make sure they work together.