An airline companion pass is one of the most valuable perks in travel rewards, because it lets a designated companion fly with you for little more than taxes and fees. For couples and families, it effectively halves the cost of every trip, and for frequent travellers it can be worth thousands of dollars a year.

The Southwest Companion Pass is the most famous version. Earn it by accumulating enough qualifying points or flights in a calendar year, and a companion of your choice flies free on every Southwest flight you take, for the rest of that year and the whole of the next. The timing trick is to earn it early in the year, maximising the months it covers.

Southwest's pass is unusually generous because it applies to every flight, including award flights booked with points. That means you can book your own seat with points and bring your companion for just the taxes, creating a trip that costs almost nothing in cash.

Alaska Airlines offers a different model: an annual companion fare discount tied to its credit card, which gives a companion ticket at a reduced fare rather than free. It is less powerful than Southwest's pass, but it still saves real money, especially on longer or more expensive routes.

Other airlines offer companion benefits through premium credit cards or elite status, but these are usually one-time certificates rather than an ongoing pass. A companion certificate that covers one trip a year is still valuable, but it requires planning to use on a route where the saving is greatest.

Earning a companion pass takes planning. Southwest's requirement is based on qualifying points earned in a calendar year, and credit card sign-up bonuses have historically counted toward it, which is how many travellers earn the pass quickly. Rules change, so check the current qualification criteria before building a strategy around them.

Timing is everything. Earning the pass in January gives you nearly two full years of benefit, while earning it in December gives you just over a year. The most successful companion pass strategies front-load the earning into the first months of the year, often through a card bonus and planned spending.

Choosing your companion matters too. Southwest lets you change your designated companion a limited number of times per year, so most people pick a partner or family member they travel with most often. Changing it frequently wastes your limited changes, so choose carefully.

Maximise the pass by flying the airline more. The pass only saves money on flights you actually take, so a companion pass on an airline you fly twice a year is worth far less than one on an airline you fly monthly. Match the pass to your real travel pattern, not to the most generous-sounding offer.

Also consider the interaction with points. A companion pass combined with a points balance is a powerful combination: your points cover your seat, the pass covers your companion, and the whole trip costs little more than taxes. That is why companion pass holders often become the most enthusiastic points collectors.

Finally, do not chase a companion pass at the expense of your finances. Earning it through spending you were already going to do is smart. Spending extra just to qualify is not, and the maths rarely works in your favour if you manufacture spending to reach a threshold.

For travellers who fly the same airline regularly with the same companion, a companion pass is the single highest-value perk available. Earn it early, use it often, and let it turn every trip into a trip for two.

A detail many travellers miss is that companion passes usually require the primary traveller to be on the same flight as the companion, and the companion's booking is tied to yours. If you change or cancel your flight, the companion's booking changes with it, which is convenient, but it also means you cannot send your companion ahead or have them travel home separately on the pass. Plan your itineraries together, and treat the pass as a package deal rather than two independent tickets.