A Kent-based tax specialist has hit out at what he describes as "shocking" levels of PAYE errors by the taxman.

Research by accountancy firm UHY Hacker Young has revealed that HM Revenue and Customs (HMRC) collected £238 million too much from taxpayers in 2009/10. This was up from £96 million the previous year.

Paul Woodward, the tax specialist in the company's Sittingbourne office, said: "We have seen a steady increase in PAYE errors over the past year. For the amount of tax collected in error through PAYE to jump 148 per cent in one year is simply unacceptable."

He also complained that Kent taxpayers are uncertain about which tax office is handling their tax because HMRC is transferring work between offices.

The data collected by Hacker Young from its offices across the UK also revealed that the amount of under-collected tax amounted to £132 million, up from £114 million the previous year.

The government is not disputing the scale of the PAYE errors. An HMRC spokesman said: "We don't regard this as acceptable so last year we introduced a new computer system which raises the bar in terms of data quality."

But the new system is taking time to bed in and both HMRC and Hacker Young agree that computer glitches had increased the volume of payment problems.

The spokesman added: "It will in the medium term significantly improve overall accuracy, reducing both under and overpayments."The HMRC spokesman added: "Our contact centres are able to quickly correct inaccuracies, when contacted by the taxpayer, in part because the new system has for the first time created a single taxpayer record which the contact centre operator can access and amend."