Law firms and lawyers who “enable” the creation of tax avoidance schemes could face heavy fines under new proposals put forward by the Treasury.

The news comes as HM Revenue & Customs launched a consultation on Wednesday (17 August) to consider sanctions for those who “design, market or facilitate the use of tax avoidance arrangements which are defeated by HMRC”.

The proposals put the spotlight squarely on lawyers, accountants and financial advisers who rake in fees for advising on failed tax schemes.

Implicated advisers, also dubbed “middle men” in the consultation papers, could face an “enabler penalty” of up to 100 per cent of the underpaid tax.

One senior tax lawyer said the news would mean “a lot of chickens coming home to roost” for certain law firms and lawyers, including senior QCs. He added: “Some private client firms are up to their eyeballs in this.”

Another lawyer said his top-tier firm had been instructed to give its blessing to a film finance scheme “but the partners refused to sign it off”. The lawyer added the next law firm the group approached “immediately signed it off”.

“People have been focusing on the banking sector for implication in tax avoidance until now, but the focus is switching to law firms and accountants,” the lawyer added.

Last year MPs on the public accounts committee accused PricewaterhouseCoopers (PwC) of promoting tax avoidance “on an industrial scale” by helping clients set up bases in tax havens such as Luxembourg.

Now the Solicitors Regulation Authority (SRA) is understood to be sharing information with the revenue related to law firms for its consultation on tax avoidance sanctions. The solicitors’ watchdog introduced an open information policy in 2012, stating it would share information with other public and regulatory bodies when requested.

The SRA last had to intervene on lawyers’ tax advice to clients earlier this year following the Panama Papers leak. The Lawyer revealed the regulator had ordered a number of UK firms named in the leaked documents to review their links to Panama firm, Mossack Fonseca.

HMRC’s consultation comes down particularly hard on QCs who advise on tax schemes following a number of cases in which silks have been named as creditors to schemes that have gone into administration.

In a case study to outline its new proposals, HMRC refers to a generic “eminent QC” who provides “plausible-sounding statements” endorsing a tax avoidance scheme. The document adds: “When users do have advice from someone with relevant expertise, it has almost always been commissioned by a party with a financial interest in the avoidance arrangements”.

It continues: “The timing and scope of advice, whether legal or otherwise, is also relevant. Because legal advice is needed to persuade users to enrol in a scheme, most often it is commissioned from legal advisors before any arrangements are implemented.”

HMRC goes on to state the ultimate burden of proving a person has failed to take reasonable care to pay its due tax sits with the revenue itself, and it could turn to both legal and financial advisers to produce “supporting evidence” during an investigation into tax arrangements.

The revenue is expected to develop a framework for tax avoidance sanctions in the next stage of its consultation.