# Learn: ancillary revenue and post-booking merchandising

Explainers on ancillary revenue, attach rate, distribution standards, and how the window after booking behaves differently from the booking flow.

Most writing about ancillary revenue is either an airline trade piece that
assumes you are an airline, or a vendor page that assumes you have already
decided to buy something. These are neither.

This section explains how ancillary revenue works, why the window after booking
converts differently from the booking flow, and how to measure any of it
honestly. It is written for commercial and distribution leads at travel
sellers, and it contains no benchmark figures we cannot source.

## Start here

Two pillar pieces carry the argument. **Ancillary revenue** covers the category
from first principles: how unbundling created it, which categories behave
differently and why, and where the revenue leaks when the seller is an
intermediary rather than the airline. **Post-booking upsell** picks up where
that leaves off, and explains why the same traveller who refused a seat fee
during checkout will pay for one a week later.

## Then the mechanics

The cluster pieces each take one thing and go deep. Attach rate is the one most
worth reading before you quote a number to anyone, because the denominator you
pick changes the answer more than the performance does. NDC versus ATPCO is the
most technical, and the one to send to a colleague who keeps asking why the
range of sellable extras differs by booking. Seat and baggage revenue cover the
two categories that carry most of the volume.

## On the missing numbers

You will notice there are no industry benchmarks anywhere in this section. That
is deliberate. We do not have figures we can attribute, and a plausible number
with no source attached is worse than no number, because it gets quoted onward.
The benchmarks piece explains where real published data lives, how to read it
critically, and how to build an internal baseline that is worth tracking.

Where arithmetic appears it is explicitly illustrative, using round numbers you
can replace with your own.

## Frequently asked questions

### Who are these written for?

Commercial and distribution leads at online travel agencies, travel agencies, and airlines. They assume you know the industry and do not assume you have worked on ancillaries specifically.

### Why are there no benchmark numbers?

Because we have none we can honestly publish. Rather than repeat an unsourceable industry figure, the benchmarks page explains how to read published data critically and how to build a baseline you can actually trust.

### Where should I start?

Ancillary revenue if you want the category from first principles, post-booking upsell if you already know the category and want to understand why the window after booking behaves differently.