Are you a member of a growing superband?

Householders who live in the most expensive properties in Britain are likely to be squeezed by a new council tax "superband".

At present, the amount people pay depends on which of eight bands their home falls into. But many town hall tax collectors and Whitehall advisers are concerned that the top band, H, for properties worth pounds 320,000 and more, is too wide a category, with those in it paying the same whether their home is worth pounds 320,000 or pounds 10m.

They believe a superband should be introduced so that those with properties worth more than pounds 500,000 pay considerably more. One way to deal with this would be to reassess properties in the top band, and move the costliest into a Band I.

The demand for a complete revaluation has become urgent, with a growing number of homes becoming eligible to be put in a top band as house prices have risen. The extent of this was highlighted this month by the news that Tony Blair's Islington home is up for sale at pounds 615,000, nearly double what he paid for it just three years ago.

Now a review of the council tax has been ordered by officials at the Environment Department. But the superband is unlikely to be introduced this year. Gordon Brown, the Chancellor, said before the election that Labour would not change the financial settlement agreed for 1997/1998, the basis on which local authorities sent out council tax bills this spring. But the need for change was made clear just after the election, when DoE officials contacted town halls. David Madison, a council tax specialist with the Local Government Association, says: "They asked if could we cope with two extra bands."

Banding was worked out according to valuations made in England and Wales in 1991. Adding an extra band on the top would not necessarily require a complete revaluation of the rest, but Whitehall might well decide to carry one out, even though it would be a time-consuming and costly exercise.