The Public Accounts Committee has attacked HMRC over its 'abysmal record' on customer service and says taxpayers rack up millions of pounds in charges trying to get through on the department's phone lines.
A report by PAC found that in 2011-12, 20m phone calls to HMRC were left unanswered, and it cost the callers £136m while they waited to speak to an adviser.
HMRC also missed its target of responding to 80% of letters within 15 days, only replying to 66% within the timeframe.
PAC chair Margaret Hodge said: 'HMRC's "customers" have no choice over whether or not they deal with the department. It is therefore disgraceful to subject them to unacceptable levels of service when they try to contact the department by phone or letter.'
Hodge criticised HMRC's new target of answering 80% of calls within five minutes, which she described as 'woefully inadequate and unambitious'.
The PAC report calculated this would leave 16m people waiting more than five minutes and is well below the industry benchmark for call responses.
'The department should set a more demanding target in the short term and a long-term target that is much closer to the industry standard of answering 80% of calls within 20 seconds,' Hodge said.
The PAC report said there were signs of a change in HMRC's attitude to customer service. It welcomed plans to resolve more queries first time and the introduction of a call-back service where this is not possible, as well as the replacement of all 0845 numbers with cheaper 03 numbers.
However, the PAC warned that the HMRC's goal of cutting the number of customer-facing staff by a third by 2015, and its recent decision to close all of its 281 face-to-face enquiry centres, could threaten its attempts to improve customer service standards.
The PAC also said that the new Real Time Information (RTI) system coming into force on 6 April, the introduction of universal credit, and changes to child benefit were likely to lead to more phone calls and enquiries.
Hodge said: 'HMRC considers that it will be able to improve service standards by reducing avoidable contact with customers and using its staff more flexibly. It may need to put in additional resources, though, to avoid the kind of plummeting performance we have seen in the past.'
