Taxpayers are being advised to think twice before attempting to file their returns over the Internet.

After a series of delays, the Inland Revenue says it is now able to accept Internet returns, but tax specialists say doubts remain about the reliability of the system.

Brian Bush, president of the Thames Valley Society of Chartered Accountants, said people should be cautious about Internet filing until there was clear evidence that it was operating successfully.

"At the moment, it's only possible to use Internet filing in limited circumstances. "There are also reports about data having to be re-entered by Inland Revenue staff, which increases the danger of mistakes and incorrect assessments, he said.