40 CFR § 63.521 - Compliance schedule.

---
identifier: "/us/cfr/t40/s63.521"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "40 CFR § 63.521 - Compliance schedule."
title_number: 40
title_name: "Protection of Environment"
section_number: "63.521"
section_name: "Compliance schedule."
chapter_name: "ENVIRONMENTAL PROTECTION AGENCY"
subchapter_number: "C"
subchapter_name: "AIR PROGRAMS"
part_number: "63"
part_name: "NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES"
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"
regulatory_source: "57 FR 61992, Dec. 29, 1992, unless otherwise noted."
cfr_part: "63"
---


# 63.521 Compliance schedule.

(a) Owners or operators of existing affected BLR and WSR sources shall comply with the applicable provisions of this subpart within 3 years of the promulgation date.

(b) New and reconstructed sources subject to this subpart shall be in compliance with the applicable provisions of this subpart upon startup.

(c) All affected sources that commenced construction or reconstruction on or before April 25, 2023, must be in compliance with the requirements in § 63.523(d), § 63.524(a)(3), (b)(3), and (c), § 63.525(a), (e), (j), (k), and (l), § 63.527(f) and (g), and § 63.528(a)(4) upon initial startup or on July 15, 2027, whichever is later. All affected sources that commenced construction or reconstruction after April 25, 2023, must be in compliance with the requirements in § 63.523(d), § 63.524(a)(3), (b)(3), and (c), § 63.525(a), (e), (j), (k), and (l), § 63.527(f) and (g), and § 63.528(a)(4) upon initial startup, or on July 15, 2024, whichever is later.

[60 FR 12676, Mar. 8, 1995, as amended at 89 FR 43268, May 16, 2024]