The chart above shows that throughout 2019 to 2020 more than 98% of tax returns were received on time, with an average for the year of 98.6%.
Mae'r siart uchod yn dangos bod mwy na 98% o'r ffurflenni treth wedi’u ffeilio’n brydlon drwy gydol 2019 i 2020, gyda chyfartaledd o 98.6% ar gyfer y flwyddyn.