Telecom now expects the costs of restructuring its business - which includes cutting up to 1230 staff - to be between $100 million and $130 million.
This is up from estimates in March which put the cost between $70 million and $80 million.
In a statement to the market today, Telecom said the increase reflects estimated non-cash adjustments - such as write-offs on assets - associated with stopping some business activities
Telecom said it expects half of the restructuring costs ($50 million to $65 million) to be non-cash in nature.
By the middle of this year, Telecom plans to cut staff numbers from the 7530 it employed at the end of 2012 to between 6300 and 6600.