Under the tax plan, plumbers, gas fitters, heating engineers and members of associated trades who have tax to pay that they have not yet told HM Revenue and Customs about can come forward by May 31 to tell the department of their intention to disclose what they owe. If they make a full disclosure, most face a low penalty rate of 10 per cent, with a maximum of 20 per cent. They have until August 31 to make their disclosure and arrange for payment to be made. After that date, using information pulled together from various sources, HMRC says it will carry out targeted investigations aimed at those who have failed to come forward and make a full declaration. Substantial penalties or even criminal prosecution could follow, the taxman warns. The plumbers tax safe plan (PTSP) is the first initiative in a campaign focused on tradespeople. It is designed to make it easy for those in the plumbing industry to put their tax affairs right. Mike Wells, HMRCs director of risk and intelligence, said: Our aim is to make it as easy as possible for plumbers to come forward, make a full disclosure and benefit from a reduced penalty. We will be using various intelligence sources to target plumbers who have not declared their full income. I strongly urge any in this group who think they may owe tax on their income to get in touch with HMRC and get their tax affairs in order simply and on the best available terms. This is the first step in enabling those with undisclosed income or gains to avoid a full tax investigation with much higher penalties. The message is clear: contact us before we contact you. INFORMATION: To start the process online complete a notification form at www.hmrc.gov.uk/plumberstaxsafeplan or ring HMRC on 0845 600 4507.