The forms, for the 2007-08 tax year, also have new deadlines for completion.
Paper forms will need to be submitted by 31 October 2008, while people who file online will have a later deadline of 31 January 2009.
The Revenue said the new form "has fewer questions, simpler language and an improved layout".
The new forms have been designed after a two-year pilot involving 7,000 self-assessment tax payers.
This is the first major revamp since the previous version was introduced in 1997, although a short version was introduced in 2005 for taxpayers with particularly simple affairs.