HM Revenue & Customs (HMRC) has announced a campaign to ensure heating engineers, gas fitters and plumbers declare their earnings and pay tax.
Tradespeople in these sectors have until 31 May to tell the department of their intention to disclose what they owe.
Those making a full disclosure will be offered reduced penalty rates of 10 per cent in most cases, or up to 20 per cent for others.
They have until 31 August to make their disclosure and arrange for payment to be made.
HMRC states that after this date it will carry out targeted investigations on those making a full declaration, with the possibility of substantial penalties or criminal prosecution.
The Plumbers Tax Safe Plan is the first initiative in a campaign focused on tradespeople and will be supported by a dedicated team.
HMRC director of risk and intelligence Mike Wells 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.”
Baker Tilly tax investigations partner Mike Down said: “Anybody with extra income or gains to disclose should seriously consider coming forward now.
“Those who do not and are subsequently found out will be liable to penalties of between 35 and 100 per cent of the tax evaded.”