Increased numbers of parents are having to pay up to £20 extra on school uniforms because children — whose larger-sized blazers, shirts, trousers, skirts are subject to VAT — are growing bigger.

Campaigners for the school uniform industry argue that the tax is unfair because it penalises children who are big for their age and does not take account of children being bigger now than they were when VAT was introduced 35 years ago.

Nick Buckland, of Price & Buckland, which makes school uniforms, said: “More and more children are paying VAT on their uniforms and we do not think this makes any sense. We now stock blazers in sizes up to 48in and are often asked to make bigger sizes to order. We recently made a size 56in blazer for a girl.”

A spokeswoman for the Schoolwear Association said that parents were unaware that school uniform was VAT— exempt only on sizes that the taxman judged would fit children under the age of 14. “This out-of-date tax ruling, dating back to the 1940s, also ignores real changes in child sizes,” she said.

The rules disadvantage those from the lower socioeconomic groups, who suffer the highest incidence of weight problems, she said, adding that about a third of children aged 11 to 15 were overweight.

Parents have to pay the full 17.5 per cent VAT on clothes designed for children aged 14 and over, including school uniform items such as blazers with a chest size of 38in and over and skirts and trousers with a waistband of 29in and over. Ties of 45in length do not attract VAT, but those of 52in do.

A recent survey of school uniform suppliers by the market research analyst Mintel suggests that these cut-off points no longer correspond to the measurements of an average 14-year-old.

Mintel concluded that over the past ten years there had been “a definite increase in average sizes”, with one independent retailer telling its researchers that children had gone up two sizes since the 1940s.

Helen Serrano, who has been running the School Togs uniform shop in Worcester for nine years, sells larger sizes routinely to children aged under 14. “Children are getting taller and wider. Many parents are aware that they are paying VAT on larger sizes and they don't think it is fair,” she said.

Nigel Evans, MP for Ribble Valley, has tabled an early day motion, which has been signed by 62 MPs from all parties, calling for a cut in VAT on school uniforms. He said: “Kids don't come in one size. We know there is a growing problem of obesity, so the anomaly in the VAT rules that exists is getting worse and the only winner is the Government.”

Brian Lightman, president of the Association of School and College Leaders and head teacher of St Cyres School, a mixed comprehensive near Cardiff, said: “Schools have been under pressure from the Government to keep the price of school uniform down by making sure that it is available from lower cost sources such as high street stores. It seems at odds with this aim to have a policy that adds to this cost,” he said.

A spokesman for Revenue & Customs said that the size at which children's clothes incurred VAT was last changed in 2002 and that tax officials were in regular contact with manufacturers about sizes.

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