Local authorities would need to evidence the need for increased rates in a given area, by reference to relevant factors (such as the three referred to earlier).
Byddai angen i awdurdodau lleol ddangos tystiolaeth bod angen cynyddu cyfraddau mewn ardal benodol, drwy gyfeirio at ffactorau perthnasol (fel y tri y cyfeiriwyd atynt uchod).