When you earn frequent flyer miles, the airline has made you a promise: a free flight or upgrade in the future. In its accounts, the airline treats that promise as a debt. Part of what you paid for your ticket is held back as deferred revenue, a type of liability. The airline only counts that money as income when you use your miles, or when it expects the miles to expire unused. For large airlines, this loyalty liability can run into billions of dollars.
Frequent flyer programs look like a simple thank-you gift. Fly often, collect miles, and one day enjoy a free trip. Behind the scenes, though, these programs create one of the most interesting accounting challenges in any industry. Every mile an airline hands out is a small promise it will have to keep later, and accounting rules make sure that promise is not forgotten.
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Why a Reward Is Treated as a Debt
A liability is something a business owes. Usually that means money, such as a loan. But a business can also owe goods or services.
When an airline gives you miles, it owes you something: the right to claim a seat, an upgrade or another reward in the future. It has received money from you, but it has not yet delivered everything it promised in return. Until it does, the accounts show an obligation.
This follows a basic principle in modern accounting rules for revenue. A business records revenue when it delivers what it promised, not simply when cash arrives. A ticket with miles includes two promises: the flight you booked, and the future reward. The airline must split the price between them.
A Simple Example
Imagine you buy a ticket for 500 and earn 2,500 miles.
The airline estimates what each part would be worth if sold separately. Suppose the flight alone would sell for 500, and the airline values each mile at about 1 cent, making the miles worth 25. Together, that is 525 of value for a 500 payment, so the airline splits the 500 in proportion:
| Part of the purchase | Share of the 500 paid | When it becomes revenue |
|---|---|---|
| The flight you booked | About 476 | When you take the flight |
| The 2,500 miles | About 24 | When you use the miles, or they are expected to expire |
When you pay, the airline receives 500 in cash. But it records no revenue yet, because it has not flown you anywhere. Both amounts sit as liabilities.
When you take the flight, the airline moves about 476 into revenue. The remaining 24 stays in the loyalty liability, sometimes for years, until you redeem your miles. Only then does it become revenue.
Real airlines use more detailed methods, based on how members actually redeem miles and what rewards cost. But the basic idea is exactly this: part of every ticket is held back for the future.
Breakage: Miles That Are Never Used
Not every mile gets used. Some members forget about their accounts, some never collect enough for a reward, and some miles expire.
In the industry, unused rewards are called breakage. Airlines study their past data to estimate how many miles will never be redeemed. If an airline expects, say, 15% of miles to go unused, it does not keep that part of the liability forever. Instead, it gradually recognizes the expected breakage as revenue over time, in step with the pattern in which other members redeem their miles.
These estimates matter a lot. Because the numbers are so large, a small change in the expected breakage rate can move an airline’s reported revenue noticeably. Auditors pay close attention to how airlines make these estimates.
Selling Miles: A Business Within a Business
Flights are not the only way to earn miles. Airlines also sell huge numbers of miles to partners, especially banks that issue airline credit cards. Every time a cardholder spends money, the bank buys miles from the airline to reward them.
For the airline, this is a very attractive business. Banks pay cash for miles today, and the airline only has to provide seats or upgrades later, often using seats that would otherwise fly empty. The cash received is again split between the miles, which are deferred until used, and other services the airline provides to the bank, such as the right to use its brand on the card.
For many large airlines, these partner sales bring in billions of dollars a year. Some analysts have described big airlines as loyalty businesses that happen to fly planes.
How Valuable Are These Programs?
The true worth of loyalty programs became very clear in 2020. When the COVID-19 pandemic grounded most flights, several airlines needed money urgently. Some used their loyalty programs as security to borrow billions of dollars.
United Airlines, for example, raised several billion dollars in 2020 backed by its MileagePlus program, and independent appraisers valued the program at more than 20 billion dollars at the time. That was higher than the stock market value of the entire airline during parts of that period.
It is worth noting that this valuation is not what appears in the airline’s balance sheet. The balance sheet shows the liability for unused miles. The value of the program as a business comes from the future cash it is expected to generate, which accounting does not record as an asset.
The Accounting Rules Behind It
Today, most large airlines follow international or United States revenue standards introduced in 2018, known as IFRS 15 and ASC 606. Both require companies to split a sale into its separate promises and record revenue for each one when it is delivered.
Before these standards, some airlines used a simpler method. For miles earned on flights, they recorded only the expected cost of providing the future reward, such as the extra food and fuel for a passenger in a seat that would otherwise be empty. The newer approach generally produces a larger liability, because it is based on the value of the miles rather than just the cost of providing them.
When an Airline Changes Its Program
Airlines sometimes change how many miles a reward requires. If a free flight suddenly needs more miles, each mile is worth less to the member.
This kind of change can affect the accounts too, because the value per mile and the expected redemption patterns may shift. An airline may need to update its estimates, which can change how much revenue it records in later periods.
Other Businesses With the Same Challenge
Airlines are the best-known example, but the same accounting applies to many loyalty programs:
- hotel chains that give points for each stay
- coffee shops that offer a free drink after a set number of purchases
- supermarkets and fuel stations with reward cards
- credit card companies with cashback or points schemes
In each case, when a customer earns a reward that has real value, part of the sale may need to be held back until the reward is delivered.
The Takeaway
Frequent flyer miles show how accounting follows promises, not just cash. The airline gets paid when you buy a ticket, but it does not treat all of that money as earned until it has delivered everything, including the free flight you might take years later. Next time you check your miles balance, you are looking at the other side of an entry sitting in an airline’s accounts as money it still owes you, in the form of a future seat in the sky.