The new tax form will cover the 2007-08 tax year
A committee of MPs says taxpayers should be given more help to understand and fill in their tax forms.
The House of Commons Public Accounts Committee said simpler forms would help raise £330m more in tax.
It also called for HM Revenue & Customs (HMRC) to improve its telephone advice service and to make its website easier to navigate.
However, HMRC has already announced the introduction of simpler forms this year and is revising its website as well.
Last month the HMRC launched a shorter form for the more than nine million self-assessment taxpayers who are due to file for the 2007-08 tax year.
It was the first big change to the forms since 1997.
"HMRC has successfully encouraged millions of people to complete and send forms to us online," said an HMRC spokeswoman.
"This has been achieved through a combination of streamlined forms, more responsive online services and media marketing," she added.
Edward Leigh MP, chairman of the Public Accounts committee said there was a lot of scope for improvement in the way HMRC dealt with taxpayers.
"Too many people are unintentionally making mistakes, resulting in an estimated underpayment of tax each year of some £330 million," he said.
"The Department is falling short of industry standards in how quickly phone enquiries are picked up and dealt with.
"Too many callers are still being shunted round the system rather than directed straightaway to the staff with the right knowledge," he added.
The committee accused the HMRC of running a website that was "a bit of a maze" and said some of its leaflets were still going over the head of people who had below average literacy.
However, the MPs acknowledged that the department's performance had improved in some areas.
In 2006-07, 72% of telephone calls were answered within 20 seconds compared with 45% the year before.
Accurate and complete advice was given 95% of the time.
However, the MPs' report pointed to the fact that 3.3 million people filled in their self-assessment tax forms incorrectly in 2001-02, understating their tax liability by £2.8bn in the process.
The MPs said £330m of that had been unintentional.