The Freedom of Information (Scotland) Act 2002 is to come into effect a year earlier than legislation intended.
Kevin Dunion, Freedom of Information Commissioner
Implementation is now expected to take place on 1 January, 2005.
The legislation will ensure that bodies such as councils, health boards and government agencies open their files to the public.
Deputy minister for finance, public services and parliament Tavish Scott said it was a "tough but deliverable target" for Scottish local authorities.
It will support more open government and lead to increased public confidence in the decisions that affect all of our daily lives
Tavish Scott, deputy public services minister
He said: "This Act will undoubtedly ensure more openness and better scrutiny of government and the public sector in Scotland.
"It will support more open government and lead to increased public confidence in the decisions that affect all of our daily lives.
"I am delighted that the important new rights of access to information held by Scottish public authorities will now be available to each and every citizen a full 12 months prior to the date set out in the legislation.
"This is the executive delivering its commitments by giving the people of
Scotland a statutory right to Scottish information for the first time."
MSPs passed the Information Bill by 74 votes to 34 in April last year.
Jim Wallace, who was justice minister at the time, said it would tackle the culture of secrecy in Scottish public life.
Scotland's Freedom of Information Commissioner Kevin Dunion was appointed in December last year.
He said he was "honoured" to fill the post and looked forward to the challenges ahead.