The job of a customs officer is to ensure that laws and regulations are complied with in connection with the import and export of goods. This includes monitoring the import of drugs, counterfeit goods (for example food and medicine), weapons, radioactive and other dangerous substances and cultural valuables, and ensuring cargo protection, disease control and product safety. A customs officer participates in the prevention of organized crime in order to counteract its effects on security in society.

Customs officers monitor ships and aircraft coming from abroad and have posts at airports, port areas, post offices, warehouses, express delivery companies and at customs offices throughout the country. In their work, customs officers use various tools and equipment such as X-ray equipment, X-ray vehicles, chemical analyzers, radiometer equipment, computers and special software for customs enforcement and surveillance, as well as narcotics search dogs.

Customs officers work in co-operation with other border inspection entities and companies as well as in co-operation with the police, for example in immigration control and regarding drug smuggling.