Outraged by your bill? Think before you jump on the council tax bandwagon

A government website crashed last week. Nothing unusual about that, you might think, but the site belonged to the Valuation Office Agency (VOA), the department responsible for the property values that determine our council tax bills. And the reason for the crash was heavy consumer traffic.

Behind all this was the ITV show Tonight with Trevor McDonald, which suggested that thousands of UK homes had been wrongly "banded" - and owners could be due a refund.

In 1993, the programme alleged, in the run-up to the introduction of council tax, there were a number of "drive-by", "kerbside" or "second gear" valuations when agents contracted by the VOA simply drove slowly up and down streets, giving rough values to whole areas at a time - and getting many wrong. An incorrect valuation, over a long period, could mean those homeowners have paid far too much tax.

The right to appeal against council tax bands - the charge made according to the size of the property and its location - is generally limited to the six months after a change of occupancy. But the VOA says it will normally review a band if requested to do so because it has a legal obligation to ensure the lists are accurate. A spokesman adds, though, that the body is satisfied the original bandings were competently calculated.

"When council tax lists were being prepared for introduction on 1 April 1993, 60 per cent of properties were banded by contractors from the private sector and 40 per cent by the VOA.

"The contractors worked under tight VOA supervision, were supplied with details of the properties concerned, and were selected on the basis of their local knowledge. They were required to put properties into one of eight council tax bands, not to carry out detailed valuations."

In the 14 years since, challenges to the bands have amounted to no more than 7 per cent of Britain's 21.1 million homes, VOA figures show.

"Between 1 April 1993 and 31 March 2006, formal challenges that resulted in a reduction (including those determined by tribunal) have been made on 4.3 per cent of total dwellings. Most of these were in the initial years, when the council tax list was first introduced."

The spokesman refuted the show's suggestion that hundreds of thousands of householders could be in line for a big refund.

"We believe the numbers extrapolated are entirely unjustified, though we accept there may be some pockets where we will need to take action."

Next month, the Lyons review commissioned by the Government will report back on whether the banding system should be updated. But in the meantime, should you take any action?

The first point to make is that while you might benefit, you can be rebanded up as well as down - so you could end up paying more.

Bandings are set by the Listing Officer at the VOA, and there are a number of reasons why a particular property's value might need to be updated - either up or down. These include the conversion of a home into flats; physical changes, such as a large extension; and part-demolition (of a conservatory, say).

Significant home improvements are the most likely explanation for why rows of houses that appear similar - the cause of many challenges - have one or two in different bands.

But whether your property was wrongly assessed in the first place is a different matter, and there are several factors to consider if you think you might have a case. First, which band your home is in depends on its value on 1 April 1991 - the official baseline date specified by the Government. General price movements in the housing market since then are not, therefore, a reason for changing your council tax banding.

Second, the bands are so wide that only someone whose home is on the cusp of two bands in 1991 prices is potentially affected.

The way the bands work means that those with the most valuable homes, and accordingly the biggest council tax bills, are least likely to discover that a revaluation will place them in a lower band. In the worst instance, if you are mistaken about the comparability of your house and your neighbours', and yours has superior features such as an extension, you could find yourself allocated to a higher bracket.

Your home may already have been checked for accuracy. After council tax was introduced on 1 April 1993, householders were given until 30 November 1993 to apply for a rebanding - so it is worth seeing if this was done.

If you live in a home built since 1991, you are even less likely to succeed with an appeal. New homes are valued as if they had been on the market in 1991.