Council tax is currently based on property values in April 1991 but the government is updating its valuation figures to take account of changes in property prices since then.
Analysis of the Halifax house price index by the Liberal Democrats shows that 82% of towns in the region have seen prices rise faster than the national average, meaning homes are likely to be moved into higher paying tax bands.
The biggest losers under council tax revaluation will be Witham, Whitstable, Littlehampton, Tring, Berkhamsted, Brighton and Hove, Teddington and Hatfield - the places where house prices have risen the fastest since 1991.
The whole of central London could be moved up a tax bracket.
Edward Davey, Liberal Democrat local government spokesman said:
'Labour is set to turn the warm glow of house price rises into a post election tax timebomb.
'The government claims council tax revaluation will make the system fairer. But this research shows it will be arbitrary, random and unfair.
'The people of the south-east are about to be penalised for the market forces that have pushed up house prices in the region.
'In areas where prices have risen the most, homes could be moved up two, three or even more bands, which could mean tax rises of 50% or more. The danger for the capital is that it could follow Cardiff, where more than 60% of homes were moved into higher bands.
'One home was moved up six bands - more than doubling that family's tax.
'Revaluation is a typical Labour stealth tax. Millions of families will see their council tax bills rocket once the election is over, but ministers have refused to come clean about it.'