We provided advice to those who were getting things wrong or where we had identified potential weaknesses, to prevent future errors which could lead to a loss of tax.
Rhoddwyd cyngor i'r rhai a oedd yn gwneud pethau'n anghywir neu pan nodwyd gwendidau posibl, a hynny er mwyn atal gwallau yn y dyfodol a allai arwain at golli treth.