14 CFR § 221.53 - Proportional fares.

---
identifier: "/us/cfr/t14/s221.53"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "14 CFR § 221.53 - Proportional fares."
title_number: 14
title_name: "Aeronautics and Space"
section_number: "221.53"
section_name: "Proportional fares."
chapter_name: "OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS)"
subchapter_number: "A"
subchapter_name: "ECONOMIC REGULATIONS"
part_number: "221"
part_name: "TARIFFS"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 40101, 40109, 40113, 46101, 46102, chapter 411, chapter 413, chapter 415 and chapter 417, subchapter I."
regulatory_source: "64 FR 40657, July 27, 1999, unless otherwise noted."
cfr_part: "221"
---


# 221.53 Proportional fares.

(a) *Definite application.* Add-on fares shall be specifically designated as “add-on” fares on each page where they appear.

(b) A tariff may provide that fares from (or to) particular points shall be determined by the addition of add-ons to, or the deduction of add-ons from, fares therein which apply from (or to) a base point. Provisions for the addition or deduction of such add-ons shall be shown either directly in connection with the fare applying to or from the base point or in a separate provision which shall specifically name the base point. The tariff shall clearly and definitely state the manner in which such add-ons shall be applied.

(c) *Restrictions upon beyond points or connecting carriers.* If an add-on fare is intended for use only on traffic originating at and/or destined to particular beyond points or is to apply only in connection with particular connecting carriers, such application shall be clearly and explicitly stated directly in connection with such add-on fare.