Apologies if this is common knowledge, or if my situation is somewhat unique, but I thought I’d share my experience hoping that it might be of value to others.

We’re a family of 3, and were hoping to be able to use Avios points, as well as a companion ticket, to travel from the US East Coast to/from mainland Europe, in a premium cabin, this summer. I was lucky enough to find availability, with the only slight wrinkle being that it was open jaw (starting New York, finishing Boston). As it was open jaw, I had to call the service center to help me with the booking, and the final cost was 270K Avios (135K x 2), and a hefty $3139.50 ($1046.50 x 3) in taxes/fees.

I had read on FlyerTalk that the fees might vary if the legs are booked separately, so I made a dummy booking and was very surprised by how much of a difference this made. Fortunately I was able to call and cancel the original booking, and then use the online tool to create the exact same trip, but this time on separate outbound and inbound bookings. Of course I was only able to use the companion ticket on one of the bookings, and had to use more Avios. The new cost was 337.5K Avios (135K x 2 + 67.5K x 1), and a more palatable $1578.12 in taxes/fees. I used 67.5K Avios more with the final booking, but the fees/taxes were $1500+ less, which is well worth it (to me at least).

I called BA to try to understand the rationale for the differences, as from a consumer perspective, everything seems identical. Unfortunately I couldn't really follow the explanation…can anybody on here dumb it down?