PwC is facing a lawsuit from British commercial property developer Revelan. The allegation is that the company provided “negligent” tax advice, which left Revelan with a tax debt of three million pounds.

Revelan, which was previously backed by US investment manager Ares, is demanding £6.6 million from PwC, according to reports in the Financial Times.

The company claimed that PwC failed to “correctly calculate the tax owed” over a five-year period, according to court documents seen by the FT.

It is the auditor’s first major lawsuit for PwC in the UK since Marco Amitrano, the firm’s former head of client and markets, took over as UK senior partner last month.

A letter included in court documents was sent by PwC to HMRC in March 2023. In it, the Big Four firm admitted that “our client’s tax affairs are complex” and the errors “were unfortunately overlooked due to the significant complexity of their tax affairs.”

It continues: “We consider that our client exercised reasonable care in the past by seeking advice from PwC in preparing its tax returns and that it could not have taken any further steps to prevent this error.”

“We therefore believe that the error was due to an error made by PwC despite the client exercising reasonable care and not to the negligence of our client.”

The errors left Revelan with a bill of around £3 million in outstanding tax debts, unpaid interest and late payment penalties.

In the letter, PwC claimed that due to “historical errors… additional indexation allowances were claimed on various property disposals, which subsequently increased the capital losses claimed on the disposal of a number of properties,” according to the FT.

Revelan argued that “PwC failed to exercise due skill and care in providing tax compliance and advisory services and acted negligently and in breach of the duty of care owed by PwC to the group companies.”

In a statement, PwC said: City AM: “We will vigorously defend this claim.”