HMRC has denied running a “deliberately poor” phone service in an attempt to push taxpayers to seek help online instead.

Nearly 44,000 customers were cut off without warning after being on hold for more than an hour last year, a report by a committee of MPs found.

It warned HMRC’s service had got even worse since then and urged the tax authority to take responsibility for failing its customers.

HMRC chief executive Jim Harra said the committee’s claims on its customer service were “completely baseless” and added “we’ve made huge improvements to our service standards, with call wait times down by 17 minutes since April last year”.

The report comes ahead of the deadline for self-assessment tax returns on 31 January, which could lead to increased demand for help.

HMRC’s phone line went dead on 43,690 customers who had been waiting 70 minutes to reach an adviser in the first 11 months of 2023-24, the Public Accounts Committee (PAC) report said.

This was because HMRC’s system could not cope with the volume of calls but customers were not warned they were about to be cut off, nor were they called back, the report added.

The figure for the number of callers cut off was published by the National Audit Office (NAO) in May last year but MPs have highlighted it among fears HMRC was running down its own helpline.

Sir Geoffrey Clifton-Brown MP, chair of the PAC, said HMRC was “excavating its way to new lows” in its customer service every year.

He added: “Worse, it seems to be degrading its own services as a matter of policy.”

The committee has called for “bold and ambitious leadership” to improve its customer services, and better tackle tax system abuse and unpaid debts.

In 2023-24, HMRC wrote off £5bn in debts as uncollectable, up from £3.2bn in 2022-23.

The report called for the authority to get a better understanding of the offshore tax gap – the difference between how much tax should be paid and what was actually paid.

It also raised concerns over decreasing rates of criminal investigation and prosecution for tax-related offences.

The recommendations come after a series of criticisms levelled at HMRC.

In March last year, it announced its phone line would be closed between April and September, but was forced to reverse its decision within 24 hours.

And in May a report found that customers were waiting an average of nearly 23 minutes to get through to an adviser.

Mr Harra, first permanent secretary and chief executive at HMRC, said: “We will always be there to answer the phone for those who need extra help. At the same time, more than 80 per cent of customers are satisfied with our digital services, with more and more people using them to quickly and easily manage their tax affairs.”