Steve Thompson, of Deloitte Dunedin, said he and his tax team spent hours on the phone trying to unsuccessfully get through to IRD on a complicated voice-recognition system.
It was practically impossible to get through the system to contact an actual IRD staff member.
''I know the staff are frustrated. The system is not working and it is an inefficient mechanism to deal with simple issues on behalf of taxpayers.
''Some of us spend an inordinate amount of time on the phone before getting kicked off because the system is overloaded.''
The system had become ''materially worse'' since the voice-recognition system was introduced, Mr Thompson said.
''I had a particular issue to deal with for an individual. I rang up and eventually got through to speak to the voice-recognition system. Once through that pain barrier, I was asked if I wanted to do the voice-recognition test for the future. I said no, and was told the phone system was overloaded and `goodbye'.
''If we can't get through I despair at the ordinary taxpayer trying to speak to someone on a simple matter or on a time-constrained issue. They won't know how to get through.''
The 90-10 rule applied to tax issues, he said. Ninety percent of issues were simple. The other 10% were complicated and needed time with an IRD staff member.
However, gone were the days when tax practitioners and taxpayers could sit down with an IRD person and tick off their list of issues in five minutes.
Now, people phoned without getting satisfaction, Mr Thompson said. A call-back system was available, but if IRD returned a call, and the person was not there to receive it, the message said to call again. That meant starting at the beginning.
The electronic mail system was also in tatters. There was about a three-week delay in responses from IRD, making time-constrained issues difficult to deal with.
''IRD needs to spend some real money in creating a proper interface between taxpayers and the system. People will be turned off and the self-assessment system will go out the door,'' he said.
Revenue Minister Peter Dunne did not respond to emailed questions sent on Wednesday.
