Shares in Meridian Energy are due to go on sale later this month with the State-owned energy company expected to be listed on the Stock Exchange in late October.
Marketing of the share sale will start on Monday evening and full details will be set out when the offer document is lodged this Friday.
In a statement the Government has confirmed investors will be able to buy Meridian shares in two installments.
They will pay for about 60% percent of the price up front and have another 18 months before they need to pay for the rest of their shares.
In the meantime investors will receive in full any dividends paid.
The Government is also putting a price cap on the shares to give certainty to investors about how much they will cost.
After the offer document is lodged this Friday the Financial Markets Authority has about five business days to review it.
New Zealanders will then have three weeks from September 30 to consider the document and apply for shares before the general offer closes on October 18. After that financial institutions will be able to bid for shares.
State-owned Enterprises Minister Tony Ryall says the process puts New Zealanders at the front of the queue for buying up to 49% of the company.
Mr Ryall has also confirmed the Government is considering options for selling Genesis Energy and Air New Zealand shares.
He says shares in Genesis Energy are likely to be put on the market in the first half of next year but no decision has been made on when to put Air New Zealand shares up for sale.
Prime Minister John Key, says the sale of up to 49% of the company will be good for investors and Meridian.
But he acknowledged the asset sales programme has faced some challenges as it struggles to make the amount of money the Government predicted.