Section 51.261 - Final compliance schedules(a) Unless EPA grants an extension under subpart R, compliance schedules designed to provide for attainment of a primary standard must-(1) Provide for compliance with the applicable plan requirements as soon as practicable; or(2) Provide for compliance no later than the date specified for attainment of the primary standard under;(b) Unless EPA grants an extension under subpart R, compliance schedules designed to provide for attainment of a secondary standard must- (1) Provide for compliance with the applicable plan requirements in a reasonable time; or(2) Provide for compliance no later than the date specified for the attainment of the secondary standard under § 51.110(c) .