The government is considering exempting "roof tax" areas from the planning gain supplement in an attempt to allay fears that developers might have to pay both.

Building has learned that the Treasury is examining proposals by English Partnerships that developers and landowners in areas that have introduced a roof tax, such as Milton Keynes, should not have to pay the PGS.

Councils and delivery agencies in the South-east growth areas have told the government they will not bring in tariffs unless they are given an exemption from the PGS.

Stephen Catchpole, chief executive of Cambridgeshire Horizons, said that it was treading carefully with its own tariff plans: "Our landowners are very concerned that they are going to be double-taxed," he said.