The research, from Citizens Advice, claims that over the last year 11,500 frustrated callers turned to Twitter to complain.
On average, those who tweeted had to wait an average of 47 minutes before their call was answered.
HMRC said the survey was “unscientific,” and “out of date”.
The official waiting time is supposed to be 10 minutes.
In one case, someone tweeted that they had tried to get through to HMRC on four occasions, and waited an hour each time.
Citizens Advice calculated that hanging on the line to HMRC for 47 minutes will, in many cases, cost consumers £4.66 in call charges.
“People are paying the price for not getting through to HMRC,” said Gillian Guy, the chief executive of Citizens Advice.
“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.”
However HMRC said it had recently taken on an extra 3,000 staff to try and lessen the delays.
“We are sorry that some customers have struggled to get hold of us, but this unscientific and out of date survey of tweets does not represent the real picture now,” said an HMRC spokesperson.
“In reality, answer rates on our phones are improving and wait times are falling.”
The study looked at 34,000 tweets made between August 2014 and August 2015.
HMRC’s chief executive, Lin Homer, is due to appear before MPs on Wednesday afternoon.
In June this year she apologised for the phone service, which she admitted was “not up to scratch”.
Government figures showed that 17 million calls to HMRC went unanswered in the previous year.