According to art. 40 from the Law on marks and geographical indications in Bulgaria:
Changes in the Name and Address of the Proprietor
Art. 40. (1) The proprietor or the applicant of a mark must notify the Patent Office of any change in his name or address within three months after the change occurs.
(2) The change shall be recorded in the State Register at the request of the proprietor.
(3) All documents of which the proprietor is to be informed shall be sent to the most recent address recorded in the State Register.
The law gives a deadline for the request but there are no provided sanctions for late registration.
The fee for registering the change in the name and the address of the proprietor is 50 BG (approximately 26 EUR).
Usually the proof of the executed change is an extract from the relevant trade / commercial register which is in charge with maintaining the registration of the companies according to the national legislation.
No legalisation is required of the document when the proprietor of a trade mark is a foreign entity – but the document has to be submitted with Bulgarian translation.
The change in the name of the company resulting in a merger or acquisition are considered as change of ownership – not change in name.