This JustLanded info is out of date (or, rather, was probably never current as it's a rather loose interpretation of the law, as actually written) and rather misleading.
Bulgaria is no longer part of the (former) Soviet Union; it's a warm and welcoming EU member country, eager to have you spend your money in our bars, restaurants, malls, and tourist hotspots. I'm confident that, as per my earlier post, you don't need to worry about registrations/inspections.
If we want to verify, it's best to refer directly to the legislation "Bulgarian Law for the Foreigners".
- Firstly, per Article 2, the word "foreigner" doesn't mean the expected meaning of "non-Bulgarian". It means someone who is neither Bulgarian, nor a citizen of any EU/EEA country, nor a citizen of Switzerland. (So the following applies to narajabi.)
Art. 2. (amend. – SG 29/07) (1) Foreigner in the sense of this Law shall be any person who is not a Bulgarian citizen or is not a citizen of another Member State of the European Union, of a state, party to the Agreement on European Economic Area, or of the Swiss Confederation.
- Secondly, per Article 28 clause 3/4, any responsibility for address registration explicitly lies with the host (not the foreigner):
(3) (suppl., SG 37/03, SG 11/05) An individual or a corporate body who has provided shelter for a foreigner shall, within 5 days from providing the shelter, inform about this circumstance in writing the office for administrative control of the foreigners or the regional police department at his location, announcing the name, the date of birth, the citizenship, the number and the series of the identification document of the foreigner.
(4) A person carrying out hotel activity, or his employee, shall register him immediately upon accommodation in a special register. The information for the accommodated foreigners shall be submitted daily by this person by 6 a.m. to the office for administrative control of the foreigners or at the regional police department at the location of the hotel.
I am pretty sure there is little or no enforcement/penalty for a host who neglects to register his friends staying over for a few weeks. Perhaps they take it a bit more seriously for hotels.
- However, thirdly, and most importantly, per "Chapter four. LEAVING OF THE REPUBLIC OF BULGARIA BY FOREIGNERS" there is no exit condition which requires the "foreigner" to provide "border guards" (I think these days we prefer "Immigration Officer") with any documentation/"receipts" regarding their address/registration during their stay. You only need to show your "travel document" (i.e. your passport). The only exception is if the foreigner is subject to a "compulsory administrative measure" (i.e. you've committed a crime or something along these lines, and the authorities have instigated some formal action against you).
- Fourthly, and finally, per Article 18 - as you'd expect when entering most countries - you'll fill in an immigration form giving your reason for travel ("tourism" / "visiting a friend") and your friend's (or your first booked hotel/Airbnb) address. So this takes care of the formalities as far as the "foreigner" is concerned. (So, if you're feeling particularly paranoid, you could make a copy/take a photo of this form so you can show it if you're unlucky enough, when leaving, to bump into an immigration official who still thinks he's a cold war border guard from 1969.)
Art. 18. (Amend., SG 42/01, amend., SG 63/05 – in force from 01.01.06) (1) At entering in the Republic of Bulgaria, the foreigner shall declare the purpose of his/her visit and shall point out in written his/her address where he/she will stay fulfilling an address card form, approved by the Minister of Interior.