Telecom says it will not be able to meet its June deadline to split into two separate companies.
The company is splitting into retail and network arms in order to take part in the Government's $1.5 billion ultra-fast broadband plan to lay fibre optic cable to 75% of homes by 2019.
Telecom says a new deadline for the split will be set when an agreement is reached with Crown Fibre Holdings, which it is now negotiating with.
A split will also require the support of shareholders.
