Struggling households owe billions of pounds in unpaid council tax, but bills are expected to keep rising in the years ahead.
Newly-published figures show £6.6bn is owed to local authorities in England, with an extra £642m having been added to those arrears in the year to April.
Separate data from Scotland and Wales means the total cumulative amount owed in the three countries has hit more than £8bn.
Campaigners have called for a more sympathetic approach to council tax debt collection, rather than the use of bailiffs.
While the government is proposing a change in the rules over the way unpaid bills are chased, the Treasury is also assuming council tax will rise by 5% a year in the future.
Councils can raise council tax by up to this amount, although they can go above this cap if they hold a local referendum or get approval from central government.