Frustrated callers tweeted HMRC over 11,500 times in the last 12 months to complain about long phone line queues.
New analysis from Citizens Advice shows people complained via Twitter about spending an average of 47 minutes in total to speak to someone at HMRC.
While official figures suggest an average wait of 10 minutes, the study from Citizens Advice shows many people are waiting longer.
One person tweeted they had tried to get through to HMRC on four occasions – waiting an hour each time.
Reasons for calling HMRC include explaining a change in circumstances that will impact on tax credits, for example losing their job or having a child, or to clarify income tax payments.
A personâ€™s tax credits wonâ€™t be adjusted accordingly if they canâ€™t update HMRC about their circumstances.Â This could mean they arenâ€™t receiving all of the support available or are being overpaid which can cause debts further down the line.
A worker may not be able to file their self assessment return on time if they cannot get through on the phone, and could face a fine for missing the deadline.
Citizens Advice carried out the study, which looked at complaints made to the @HMRCgovuk Twitter account between September 2014 to August 2015, after people seeking help from the charity had reported not being able to get through to resolve matters with HMRC.
The charity helped with 295,000 queries in the last 12 months which could require people to contact HMRC.
Three out of four of these cases specifically relate to tax credits, the others include Â income tax, National Insurance Contributions and Child Benefit.
In addition, every month 67,000 people visit the tax credit pages of the Citizens Advice website making it the third most visited section of the site.
HMRC phones lines are a 0300 numbers meaning calls are charged at the same rate as a standard landline call and could be included in some phone packageâ€™s free minutes.Â However if a person is waiting 47 minutes it could cost them Â£4.66.
The charity is also warning that the roll-out of Universal Credit and changes to tax credits could mean waiting times will further soar as more and more people try to speak to someone about their circumstances.
Citizens Advice Chief Executive Gillian Guy said:
â€œPeople are paying the price for not getting through to HMRC.Â From fines for not completing a tax return in time to under or overpayments for tax credits, people can be left out of pocket because they cannot speak to HMRC on the phone.
â€œWork and caring responsibilities means not everyone will be able to wait for three quarters of an hour to ask HMRC a question.
â€œWe have consistently raised this issue with the Government.Â But evidence from across the Citizens Advice service, and our new research, shows HMRC is still failing to provide a timely service.
â€œThere is already a clear demand to be able to speak to HMRC.Â With the roll-out of Universal Credit and big changes to tax credits just around the corner this is only going to grow.Â HMRC needs to urgently address the problems many people are experiencing with phone lines.â€
Citizens Advice advisers acting on behalf of clients also face long queues for the intermediary line, which organisations like Citizens Advice can use to make direct contact with HMRC staff.
Peak months for complaints via Twitter include:
- January 2015 when income tax self assessments are due by the end of the month (1,133 tweets).
- June and July in the run up to the 31 July deadline for tax credit renewals (1,443 for June and 1,128 for July).
Data published by Citizens Advice earlier this year shows the number of people seeking advice for complaints about public services has grown over the last few years.Â There has been a 51 per cent increase between 2011-12 to 2014-15.Â The charityâ€™s evidence shows people are struggling to access the public services they need and then struggling to complain when they donâ€™t.