Can anyone advise if the property taxes applicable to a house sale are set at contract date or at completion date? This is a re-sale property which we are about to sell.

If you are talking about the "transfer tax" , then it is applicable when the transfer is registered at the Land Office, it has nothing to do with the date anyone entered into a contract to sell or purchase property

I was thinking about all the taxes - Transfer Fee, Specific Business Tax (if applicable), Stamp Duty, Withholding tax. I understand that reductions are currently in place, now extended to end May I believe.

it is only the transfer tax which is on a tax holiday at 0.10% of transaction. this will increase back to 2-3% after 31 maty

as in other post,, is not related to dates on contactcs, if you tansfer on or before 31 may its at the reduced rate, if after 31 may its the new rate..

the transfer fee is fixed flat - 600 baht

the SBT has not been reduced..still 3.3% - this is the sellers responsibiltiy..

only transfer fee and transfer tax are buyers responsibility or 50/50 if you have negotiatedthat with buyer..