IATA describes an ADM as an accounting tool airlines use to collect adjustments on electronic tickets and refunds issued by agents, governed by its Resolution 850m. The airline raises it in IATA’s BSPlink system, giving the reason and the type of transaction: an issue, refund, exchange or EMD. IATA does not check fare calculations itself. Each airline audits its own sales and can raise an agency credit memo (ACM) instead if it owes the agent money.

How it works through BSP

• Dispute window. The agent has 15 days from issue to dispute an ADM in BSPlink. The airline then has 60 days to accept or reject the dispute.

• Billing. An accepted dispute deactivates the ADM. Otherwise it goes into the agent’s BSP billing, due on the remittance date. A dispute can still be raised after billing, up to 12 months from the transaction, but the agent pays the full billing meanwhile. Some airlines allow less time.

• Time limit. IATA’s published copy of Resolution 850m says ADMs go through BSP only if issued within nine months of the final travel date, or of a refund. Later debits go directly between airline and agent. Virgin Atlantic’s policy matches.

Why it matters for travel businesses

An ADM can arrive months after the sale. IATA says the most frequent errors involve complicated fares, exchanges and refunds. An airline can also raise one when a customer disputes a card payment and the agent cannot supply evidence in time.

Policies differ by airline. Virgin Atlantic, for example, usually adds a £30 charge to an under-collected fare, tax or fee. For a ticket issued after the ticketing time limit, it charges £50 to £250 depending on cabin. It says it will not issue ADMs on bookings made and ticketed through its own NDC channels, except for reasons such as fraud or breaches of fare rules or its booking policies.