Patents of Invention

– Law on Patents and Utility Models Registration, in force since June 1, 1993, with latest amendments as of December 13, 2019.

Membership in International Conventions

– Paris Convention for the Protection of Industrial Property, Stockholm Act.
– Convention Establishing the World Intellectual Property Organization (WIPO), since May 19, 1970.
– Budapest Treaty on the International Recognition of the Deposit of Microorganisms for the Purposes of Patent Procedure, since August 19, 1980.
– Patent Cooperation Treaty (PCT), since May 21, 1984.
– WTO’s TRIPS Agreement, since December 1, 1996.
– The Hague Convention Abolishing the Requirement of Legalization for Foreign Public Documents (Apostille), since April 29, 2001.
– Strasbourg Agreement Concerning the International Patent Classification, since November 27, 2001.
– European Patent Convention, since July 1, 2002.


Applicant: inventor or his legal successor (individual, industrial firm or company). 

Foreigners and nationals not living in the country: must appoint a representative. 

Protection of foreigners: same as for nationals. 

Naming of inventor(s): obligatory. 

Nature of the invention: patents are granted for inventions, which are new, involve an inventive step and are industrially applicable.

Novelty: international.

Novelty grace period in favor of the inventor: six months.

Exceptions to protection: no patents are granted for (a) inventions which use would violate the social order or good morality, including the methods for cloning of humans, methods for altering the generic identity of human embryo, use of human embryo for industrial or commercial purposes, methods of modifying the generic identity of animals, which would cause suffering without any substantial use from a medical point of view for humans or animals; (b) methods for treatment of humans or animals through therapy or by surgical way and diagnostic methods practiced on them, this restriction being not applied for products and substances used in these methods; (c) plant varieties and animal breeds as well as essentially biological processes for their production. Products consisting of or containing biological material, as well as the methods of obtaining, processing and use of biological material and biological material isolated from the natural environment or obtained by a technical process are patentable.

Confirmation patents: not provided for.

Priorities: one or more; partial priorities.

Territory covered: the territory of the Republic of Bulgaria.

Filing requirements for an application (to be sent to resident agent):
1. Power of attorney (not legalized);
2. 3 specifications;
3. 3 sets of drawings, size 21 x 29.7 cm (format A4);
4. Certified copy of home application, if priority is to be claimed (can be filed within three months from the filing date).

Electronic filing: available.

Electronic signatures: are not accepted (only wet signatures).

Filing without one or more requirements: possible; the application must contain the name of the applicant, the title of the invention and the specification, which discloses at least its essence. A Bulgarian translation must be filed within three months. 

Filing without power of attorney: possible; must be filed within three months. 

Claiming priority: can be claimed within two months after the filing date and the certificate of priority has to be filed within three months after the filing date.

PCT applications: time limit for entering the national phase: 31 months from priority date.

Rights deriving from a European patent: Bulgaria can be a designated country.  The time limit for entering EP regional phase is 31 months under both Chapters I and II.  European patent validation requirements: (a) appointment of a local representative is required; (b) a Bulgarian translation of the full specification (patent description, claims and figures) must be presented within a non-extendible term of three months after the date of notification for granting of the European patent in the European Patent Bulletin; (c) the minimum time period for paying the respective annuity due at validation is two months after publication.


Amendment of application: possible only if the amendments do not go beyond the initial disclosure. 

Process claims: in the case of infringement of a product obtained by a patented method for a new product, the burden of the proof lies with the infringer.

Publication: the application is published after eighteen months following the filing date, or, respectively, the priority date. Expedited publication is admissible by request of the applicant. 

Prior user: can only use the invention for his own purposes. 

Examination: by the expiration of thirteen months from the filing date, respectively from the priority date, the applicant can file an application for examination and pay the respective examination fees. If such application is not filed within fifteen months from the priority date, the patent application can be transformed into a utility model application. The examination is carried out in order to establish the presence or the absence of the requirements for patenting an invention.

Appeals: can be filed against a decision for rejection of an application for a patent issued by the Patent Office: (a) (first step) at the “Appeal Department” of the Patent Office; (b) (second step) at the court. 

Division: possible during procedure. 

Opposition to application filed: possible before the Patent Office within three months after the date of publication of the patent application, but the opposing party cannot become a party in any procedure.

Provisional protection: for the time from the publication up to the grant of a patent, ad interim protection is provided.


Delivery of document: after publication of the decision to grant a patent. The publication is made immediately after the expiration of the three-month period following the decision to grant the patent. The Letters Patent is issued within one month after the publication.

Publication of granted patents: in the Official Bulletin of the Patent Office. 

Beginning of protection: from the day of filing of the application.  

Duration: twenty years.

Annuities: due within three months after the granting decision (accumulated). Thereafter, in advance for the next patent annuity and the payment must be made not later than the last day of the month during which the previous patent year expires.

Annuity grace period: six months with fine.

Marking of patented goods: not obligatory but advisable. 

Text of marking: “Bulgarian Patent No….”. 

Amendment of issued patents: possible in exceptional cases on the decision of the Patent Office. 

Assignment: possible, but must be registered.

License for exploitation: the patentee has the right to grant a license for the use of the patent. The contract or relevant document stating the granting of a license should be registered at the Patent Office in order to be valid against third parties.

Working: not compulsory. Manufacture, sale or importation is considered as validly working the invention. See “Compulsory licenses” below.

Validation of invalidated patents: not possible.

Modification of Protection after Registration

Opposition to granted patents: (a) if the invention does not correspond to the requirements set in the law; or (b) if the court ascertains that the actual inventor or co-inventor is another person.

Compulsory licenses: any person who has made an unsuccessful attempt to obtain a contractual license under reasonable conditions can petition the Patent Office for concession of a compulsory license in his favor for the use of a patent protected invention provided that at least one of the following conditions is present: (1) failure to use the invention for a period of four years from filing of the application for a patent or of three years from the grant of a patent, whichever is later; (2) insufficient use of the invention to satisfy the needs of the national market, within the time limits as per point (1) above, unless the patent owner proves the existence of valid reasons for failing to meet the needs; (3) declared national state of emergency; However, the petitioner has to prove that he is in a position to use the invention within the limits of the requested compulsory license. A compulsory license can be granted if required by public interest and if negotiations for contractual license have not been carried out. Compulsory license can be granted in favor of a patent owner whose invention is included in the scope of another patent, if the patent owner refuses to grant a license at fair conditions.

Nullification: possible during the entire life of the patent in case (1) the invention is not patentable; (2) the essence of the invention is not disclosed clearly; (3) a court decision establishes that the patent owner does not have a right on the patent. Disputes concerning the inventorship or co-inventorship of inventions are decided through legal proceedings at the Sofia City Court.

Infringement: appeal to the court for damages and losses and/or for injunction against the infringement. Border measures are also available.

Supplementary Protection Certificates (SPCs)

Supplementary Protection Certificates for medicinal products and plant protection products are introduced with the amendments of the Patent Law in force since November 9, 2006 and are granted under certain conditions, which are harmonized with Regulation 1768/92/EEC and Regulation 1610/96/EEC.

Application: must be filed within six months after the date of the authorization to market the products in Bulgaria was granted (or the date of the first authorization in case the authorization for Bulgaria is not the first one) or within six months after the date of grant of the patent, in case the authorization to market is granted before the grant of the patent. The application is filed at the Patent Office and must be filed only by the patentee. 

Applicants not living in Bulgaria: must appoint a local representative.

Filing requirements: application for issuing of a SPC, which contains the name and address of the applicant, the relevant patent number and title, the number and the date of the first authorization for market in Bulgaria or in case the first authorization is not for Bulgaria – the number and the date of the first authorization for the EC. With the application the following documents must be attached: (1) a copy of the authorization to market according to Art. 3(b) of the Regulations in which the product is identified and which contains the number and the date of the authorization and a summary of the characteristics of the product; (2) if the authorization is not the first authorization to market within the EC, information about the identity of the authorized product and the legal provision according to which the last mentioned authorization to market has been granted, together with a copy of the notification with which the authorization was published; (3) a simply signed power of attorney.

Term of protection: maximum five years from the date on which the basic patent expires.

Patent annuities: payable at once during the latest year of the patent but not later than the termination of the patent except in the cases when the decision for granting the SPC is taken immediately before the expiration. In this case the patent annuities are paid within two months after the date of receipt of the decision.