How a US VIN is built: what NHTSA's 49 CFR Part 565 requires, from the 2008 final rule to the current text

Every passenger car, truck, bus, trailer, incomplete vehicle, low-speed vehicle and motorcycle sold in the United States carries a vehicle identification number (VIN), and the rules for that number live in 49 CFR Part 565, issued by the National Highway Traffic Safety Administration (NHTSA). The regulation is US-specific: it does not govern how other markets number their vehicles, so a European or Chinese-market VIN may follow different national rules. Part 565 specifies the format, content and physical requirements for the VIN system and its installation.

The stated purpose is practical rather than bureaucratic. A VIN under Part 565 is a series of Arabic numbers and Roman letters assigned to a motor vehicle for identification purposes, and NHTSA describes VINs as serving to increase the accuracy and efficiency of vehicle recall campaigns, as well as being the key identifier in data systems tracking compliance with federal importation regulations, vehicle registrations, insurance coverage and motor vehicle crashes.

The 2008 rewrite and why it happened

In a final rule published in the Federal Register on April 30, 2008 (73 FR 23367), NHTSA amended Part 565 so that the supply of manufacturer identifiers and VINs available under the regulation would be sufficient for at least the next 30 years. The agency acted in response to a petition for rulemaking, revising where certain information must be communicated in the VIN and the characters that may be used in some of the 17 positions for passenger cars, multipurpose passenger vehicles, and trucks with a gross vehicle weight rating of 4536 kg (10,000 lb) or less.

NHTSA said the changes would have two primary effects: the need to issue new manufacturer identifiers, particularly for large manufacturers, should be drastically reduced, preserving the remaining character combinations for longer, and the changes would substantially increase the number of combinations of characters available.

When the requirements apply

The applicability dates in the current eCFR text (displayed as of September 9, 2026) turn on the build date and the tenth character of the VIN. Subpart B, the current VIN requirements, applies to the listed vehicle types manufactured on or after October 27, 2008 whose VINs have a letter "A" or "B" in the 10th position, and to vehicles manufactured on or after April 30, 2009.

The regulation also contains a transition subpart. Subpart C sets out alternative VIN requirements for a limited period, and under the application section, motor vehicles identified by their manufacturer as model year 2009 or earlier must comply with subpart C. Vehicles built between April 30, 2008 and April 30, 2009 whose VIN does not have an "A" or "B" in the 10th position, and that are not identified as model year 2009 or earlier, also fall under subpart B per the 2008 rule's framing.

Who assigns the identifiers, and the replica carve-out

US manufacturers do not ask NHTSA for their manufacturer identifier (the World Manufacturer Identifier, or WMI). Per the March 9, 2022 final rule, they contact SAE International directly to request the assignment of a manufacturer identifier, by telephone or in writing to SAE's Warrendale, Pennsylvania address, Attention: WMI Coordinator.

The 2022 rule, which established the FAST Act replica-vehicle program, added requirements for replica vehicles. NHTSA sought to ensure replica vehicles are properly identified as replicas in their VINs, and that the VIN denote the make, model, and model year of the original vehicle. The agency also noted that replica motor vehicle manufacturers must obtain unique manufacturer identifiers, and that the replica program applies to low-volume manufacturers — a manufacturer producing more than 5,000 motor vehicles annually would not qualify. The replica provisions apply in the United States market under the FAST Act program as finalized in that rule.

• Check the regulation itself: the current text of 49 CFR Part 565 is on the eCFR (ecfr.gov), which shows title 49 up to date as of its display date; the eCFR is a continuously updated online version and is authoritative but unofficial.
• Check the rulemaking history: the April 30, 2008 final rule is Federal Register document 08-1197 (73 FR 23367), and the March 9, 2022 replica-vehicle rule is on federalregister.gov; both pages link to the official PDF on govinfo.gov, which the Federal Register site identifies as the official electronic format.
• Check your own vehicle's VIN: the 17-character requirement for vehicles manufactured for sale in the United States comes from Part 565; for the make, model year and other encoded details of a specific vehicle, rely on the manufacturer's documentation or official records such as your state registration, which the rule documents list among the data systems that use VINs.