The tax due on that transaction is now £18,235.29, less £13,500 that has already been paid, so only £4,735.29 needs to be paid on the further return in respect of the first transaction.
Gan fod treth yn daladwy yn awr ar y trafodiad cyntaf pan nad oedd treth yn daladwy gynt, bydd gofyn dychwelyd ffurflen dreth bellach ar gyfer y trafodiad hwnnw.