Kent businesses trading above the Vat threshold of £73,000 without registering for the tax could be in for a nasty shock.

HM Revenue & Customs (HMRC) is planning a campaign to crack down on Vat rule breakers.

The message will be simple: Pay up now or you may regret it later.

HMRC campaigns are aimed at reducing the "tax gap" by focusing on areas where a significant underpayment has been identified.

Jon Cleverdon, director of Broadstairs-based Cleverdons chartered accountants and business advisors, said: "Previous campaigns have targeted offshore investments, medical professionals and people working in the plumbing industry. Businesses are being given the opportunity to make a voluntary disclosure to HMRC and minimise their Vat liability.

"HMRC has indicated it will offer businesses which come forward voluntarily, by September 30, 2011, lower penalties for prompt action or in some cases no penalties at all."

Mr Cleverdon said the amnesty would give unregistered companies the chance to get their business affairs in order.

"Once the amnesty is finished HMRC intends to target the businesses it believes are trading over the threshold. Businesses or inviduals who remain unregistered after the amnesty period will face a detailed investigation into their affairs and will be subject to substantial penalties and interest in addition to the tax due, if it is found that they are breaching the regulations."

HMRC says it provides simple, straightforward opportunities for customers to put their records in order on the best possible terms, followed immediately by activity focused on the non-compliant who choose not to take up the opportunity.

HMRC has raised over £500m from voluntary Vat disclosures and a further £100m so far from follow-up activity.