Qatar search from US cities to DOH always routing through UK?
 

I had read on some websites I could search Qatar availability using Avios search and have seen screen shots showing direct to DOH flights from Houston, Chicago, Washington etc. on ba.com/avios search. Today if I search various dates in May, all flights want me to go to UK first and pay sucky taxes.

Any ideas/help please?

If QR has award availability it will be shown below the BA options. If you don't see any QR options then there is no award availability.

Transit through the UK doesn't trigger any taxes at all, although you'll pay passenger service charge (which is too high, but on the scale of things not really that much!). BA may levy extra YQ on routes to/from the UK, but that cash goes to BA, it's certainly not 'tax' :)

BA.com has a rather LON-centric view of the world, and certainly doesn't show all possible partner routings (how could it?)

To the OP: you may have to search sector by sector (first for $origin-DOH, then for DOH-$destination); if you can find both you'll have to phone BA to book.