If I were you I would do it in 20K GBP lots. As long as you do it this year there will be no problems with Taxes. The new taxes start from 1st of January. So anything transferred before that date will not get caught up in the new rules. Besides which, I doubt it will be a problem even after Jan 1st. Thai Revenue department aren't set up for dealing with the issues that arise from the new rules when dealing with expats and double taxation etc, etc.