Skip lagging on international booking
 

I need to book a one-way international TATL flight in December, but one way prices are full flex with R/T about 1/5th with a sat night stay.

Because of the limited schedule into January available now, I’m only able to book the return about 5 days after, so unlikely to use it. I’d like to book outbound ASAP as looking to use 2 x expiring SWUs on currently available upgrade inventory.

given AAs crackdown, is abandoning the return segment considered against the terms of carriage. If so, With the current flexibility booking policy, can I book now and rebook the return segment further out once the schedule opens up (first segment will originate in UK).

Why not simply book the round-trip now and then move the return to some later date when it might be useful? No change fees and you could select a date when there is no fare increase. Perhaps even a fare break which would get you a credit for future use.

Indeed, I would not expect cheaper fare buckets to open up for a good long while, perhaps in the Fall.

Exactly, or the OP can use miles to book a one-way international ticket which in economy, AA typically offers at fairly low one-way mileage rates.

I can’t use the SWU on a Y miles booking, and booking in J with miles is about 100K miles plus ex-LHR taxes of about $300 so not as good a return

Just book the roundtrip with the return on the dummy dates 5 days later. As mentioned you can change the return dates later for no fee if you can use it, otherwise just throw it away. Nothing "bad" will happen whatsoever as long as you're not doing this every week, or anything like that.

Just book the RT with the dummy return... heck, if schedule changes result in a cancelation on the return, you might even end up being eligible for a substantial refund. A lot can happen in 11 months...

Indeed. The chances that a given flight will be significantly changed or cancelled when booked more than 30 days out is pretty significant during the pandemic.

No need to engage in ticket fraud in the first place.

Just something to think about is a maximum stay requirement. Not sure if they are still putting those on low-ball fares but I seem to remember them as 30 days a few years ago.

Max stay is generally 12 months these days even on deep discount fares. I wouldn't count on being able get a refund on return flight while keeping outgoing flights just because of a schedule change or flight cancel as you would no longer meet roundtrip fare requirements. They would certainly allow you to reschedule flights, but if you wish to cancel for refund it will likely be both ways or none.

If you fly from LHR (or most UK airports) in J you will pay the increased UK APD no not matter if an award, upgrade or cash ticket. So ex LHR/UK real taxes are not part of equation. The BA/AA award surcharges are not taxes.

APD should be approximately $200 in J, so anything above that is an air carrier fee, not a government tax.