40 CFR § 85.2303 - Duration of model year.
---
identifier: "/us/cfr/t40/s85.2303"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 85.2303 - Duration of model year."
title_number: 40
title_name: "Protection of Environment"
section_number: "85.2303"
section_name: "Duration of model year."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "85"
part_name: "CONTROL OF AIR POLLUTION FROM MOBILE SOURCES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "42 U.S.C. 7401-7671q."
cfr_part: "85"
---
# 85.2303 Duration of model year.
A specific model year must always include January 1 of the calendar year for which it is designated and may not include a January 1 of any other calendar year. Thus, the maximum duration of a model year is one calendar year plus 364 days.