Small firms have less than a month to contest the level of business rates they have paid over the past five years.

“Any business owners who believe they have been charged too much for their rates since the last revaluation in 2005 have until March 31 to appeal,” warned the Forum of Private Business.

The FPB said it believed around 160,000 small businesses had already won backdated reductions in their rates since April 1, 2005, when the current rateable period began.

However, many more could be eligible.

There are two main grounds for appeal, the FPB said.

1. Businesses that pay more than neighbouring properties. The Valuation Office Agency (VOA) website at www.voa.gov.uk will allow businesses to find out what neighbouring firms are paying and whether or not they have appealed.

2. Businesses that have suffered a material change in their surroundings since 2005 that has had a detrimental effect on trade. Streets closed off because of roadworks, a high proportion of empty shops or a change in the size or use of the business premises can all count here.

The FPB also pointed out that firms can also take the opportunity to appeal against the business rates that come into effect in April.

As it pointed out, rateable values were controversially re-assessed just before the credit crunch sent rents and property values tumbling.