Door-to-door salespeople have until the end of February to come clean about any tax they owe in return for a reduced penalty.
The direct selling disclosure campaign is HMRC's latest effort to target a specific sector suspected of evading tax.
HMRC defines direct selling as retailing to customers, usually door-to-door or in customers' homes or the workplace. Direct sellers are often self-employed and get a commission on sales they make. People earning money in this way are typically referred to as agents, consultants, representatives or distributors.
To take part in the disclosure initiative, taxpayers must inform HMRC about any amount due and make arrangements to pay tax, interest and penalties by 28 February 2013.
HMRC has run more than 10 amnesty-based tax campaigns since 2011, targeting sectors ranging from medics and plumbers to restaurant owners and people with offshore investments. In common with the other campaigns, those who opt to make voluntary disclosures will be entitled to pay reduced penalties (10% of tax owed for carelessness, 20% for deliberate understatements or non-disclosures) compared to penalties of up to 100% of the tax due if HMRC identifies them without prompting.
The amnesties are part of a much wider dash for cash across the department, in which the government committed £917m in funding from 2011/12 to tackle tax evasion, avoidance and fraud. The target is to raise an additional £7bn each year by 2014/15.