Larimer County residents are required to obtain a certificate of emissions control for vehicles within a designated area of Larimer County. The test is required on:

• Vehicles being registered for the first time in Larimer County
• Vehicles currently registered in Larimer County upon renewal
• Newly purchased vehicles
  • Gasoline vehicles are exempt from an emissions test for the first seven model years.
  • Diesel vehicles are exempt from an emissions test for the first four model years.
• Transfer of ownership
  • If the ownership of a gasoline vehicle is being transferred in the last year of the seven year exemption, an emissions test will be required. For example, in 2025, an emissions test will be required if the ownership of a model year 2019 is transferred.
  • If the ownership of a diesel vehicle is being transferred in the last year of the four year exemption, an emissions test will be required. For example, in 2025, an emissions test will be required if the ownership of a model year 2022 is transferred.
• Collector vehicles
  • Vehicles that are 1975 and older registered with 5-year Collector plates are not required to have an emissions test.
  • Vehicles that qualify for the 5-year Collector plates but require an emissions test are model years 1976 - 1990. A completed DR2839 Collector's Item Affidavit is required.