Rules on estimating contract values are necessary as a result of there being different thresholds (and consequently different obligations on contracting authorities) for different types of contract.
Mae angen rheolau ar amcangyfrif gwerthoedd contractau am fod trothwyon gwahanol (ac, felly, rhwymedigaethau gwahanol ar awdurdodau contractio) ar gyfer mathau gwahanol o gontract.