In particular, this will be due to higher rate refunds (relating to transactions which were effective during 2018-19) continuing to be made for the next few years.
Yn fwyaf arbennig, bydd hyn o ganlyniad i ad-daliadau cyfradd uwch (yn ymwneud â thrafodiadau a ddaeth i rym yn ystod 2018-19) yn parhau i gael eu gwneud am yr ychydig flynyddoedd nesaf.