Royal Mail will offer shares between 260p and 330p each in its London IPO valuing the state-owned service between £2.6bn and £3.3bn.
In a statement the government said that 10% of the shares will be given to around 150,000 “eligible UK-based Royal Mail employees”.
Under its privatisation proposals, the government will sell between 40.1% and 52.2% of shares.
The market debut is expected on 11 September and the last date of applications is 8 October. The minimum application for the public wishing to purchase shares is £750, and £500 for eligible Royal Mail employees.
The Communication Workers Union (CWU) has “criticised” the privatisation and a strike ballot will close on 16 October.
CWU general secretary Billy Hayes said: “It seems remarkable that the prospectus is being issued on the same day that postal workers are being sent ballot papers for strike action.
“Royal Mail is profitable and can continue to be successful in the public sector. The sale is driven by political dogma, not economic necessity, and postal workers and the CWU will continue to fight to save services as well as defend their terms and conditions,” he added.