The deadline is currently December 30, 2006. Nazarbaev suggested an extension to April 1, 2007.
Nazarbaev also asked parliamentarians to amend the capital-amnesty law to enhance provisions on confidentiality.
The government hopes the amnesty, which aims at denting shadow economy, will bring in additional budget revenues worth about $30 million.
In his address to parliament, Nazarbaev also vowed to continue steps toward reforming public administration and fighting corruption.
He said the number of civil servants should eventually be reduced by 30 percent, with the savings to be used to make salaries in the public administration "comparable to those in the private sector."