Accountancy firm RSM Tenon has been caught up in a legal spat with Peak Performance, the company behind the K2 tax avoidance scheme used by TV comedian Jimmy Carr.

The row centres on allegedly unpaid commissions due to Peak Performance, which ran the Jersey-based K2 scheme. It has lodged claims worth £2m following the closure of RSM's specialist tax planning division last May, according to The Times.

Earlier this year, the TV funnyman was forced to offer a groveling apology after an investigation by The Times exposed the comedian had used the scheme to funnel £3.3m a year from stand-up tours, TV appearances and DVD sales into the Jersey-based K2 scheme.

The K2 scheme is responsible for sheltering £168m a year from HMRC. The taxman has previously said that wealthy individuals' tax avoidance costs the nation £4.5bn out of an estimated £7bn loss to Treasury coffers each year.

Carr was immediately labelled a hypocrite after he made a gag about tax avoidance on 10 0'Clock Live show: 'Why don't you apply for the Barclays' 1% tax scam? You will need the world's biggest, most aggressive team of blood-hungry amoral tax lawyers. If you meet the criteria, you'll pay 1%, like Barclays do.'

The offshore scheme he used was understood to potentially slash his income tax to just one 1%.

RSM Tenon revealed a £101.8m in pre-tax losses in its annual results this week, partially explained by a £73.1m exceptional cost of which £63.7m was attributed to a goodwill write-down. In addition the firm booked a £4.3m cost resulting from a settlement with the FSA after it was fined in 2010 for failings concerning its advice and sales processes for Lehman-backed structured products and for failing to prevent inappropriate advice for structured products and pension switching.

The firm's lenders, Lloyds, confirmed facilities of £93m up to the end of December 2014.