Fel yn achos unrhyw system drethi, mae rhai yn benderfynol o osgoi'r ardrethi annomestig y maent yn atebol i'w talu. Mae Llywodraeth Cymru wedi ymrwymo i dorri ar y cyfle i osgoi talu trethi a helpu sefydliadau i ymchwilio'n fwy effeithiol i achosion.  Efallai mai lleiafswm bach o drethdalwyr annomestig sy'n osgoi talu trethi, ond pan nad ydynt yn cyfrannu'n deg mae gwasanaethau lleol, y gymuned ehangach a threthdalwyr eraill ar eu colled.
As with any tax system, there are those who set out to avoid their non-domestic rates liability.  The Welsh Government is committed to reducing the opportunities for avoidance behaviour and to helping organisations investigate cases more effectively.  While avoidance may involve only a small minority of ratepayers, when they do not contribute their fair share it is to the detriment of local services, the wider community and other ratepayers.