Delays in processing paperwork by HM Revenue & Customs are slowing down refund payments that are crucial to some businesses, an accountancy firm has warned. The warning comes from PKF accountants who claim that a new unit to investigate tax refund claims set up by HMRC in Bristol can add at least a month on to the refund process. The taxman makes security checks on 10% of tax refund claims to check for fraud, but if a claim doesn't pass the initial test it can be sent on to this unit without notification to the taxpayer. The unit only accepts written communications, which means there is no way to speed up the process or find out why a refund has not been made, the accountancy firm says. In the pre-Budget report last year, chancellor Alistair Darling announced there would be a temporary extension to the loss carry-back rules that allowed losses to be carried back up to a period of three years. But PKF says the small print of the announcement said that refunds would not be made until the Budget, which means 22 April at the earliest. Some have said this could even be delayed until the Finance Bill achieves Royal Assent- likely to be July. PKF tax partner Peter Harrup said: 'There is a sharp contrast here with the government's statements on 'Prompt payment' to suppliers: it aims to pay suppliers within 10 days and promises to pay within 30 days. The circumstances may be a little different, but the impact of a delay on a struggling business can be just the same - a cashflow crisis.' 'While I doubt that HMRC is deliberately delaying tax refunds to protect the government's own cashflow, it must improve its performance on making refunds at this difficult time for many businesses,' he added. A spokeswoman for HMRC said: 'HMRC aims to deal with claims to repayments as quickly as possible. In practice, though, it is not always possible to prioritise repayments.' 'HMRC have a duty to satisfy ourselves that repayments are in fact due and payable. It is sometimes necessary to make detailed checks of repayment claims. So it will sometimes take us longer than normal to make any repayment, particular at peak times of year,' she added.