Chief executive Andy Baker is leaving after six years and his job will be deleted.
A ll non-call centre workers face being TUPE’d across into the parent company from February 2020.
Bosses say under the proposals a “tiny” number of duplicate posts will be deleted but affected staff will be offered other jobs in the company. Redundancies are “very unlikely.”
The move aims to streamline the businesses, which include mobile operator EE, and prepare Plusnet for further growth.
Mr Baker said there had been an “extended series of conversations” about his and the firm’s future for much of this year.
He added: “The time is right. I have had an amazing six years. But I didn’t want to outstay my welcome. This is about the next chapter in Plusnet’s evolution.”
Turnover and staff numbers have doubled during his tenure, to £410m and 1,678 people at sites in Sheffield and Leeds.
Gross profit this year was £186m while customer numbers were up 10 per cent.
Mr Baker starts a new job outside Sheffield in January.
Plusnet customers will not see any changes, he added, but it will be easier and quicker to launch new products and “hopefully accelerate growth.”
He added: “Plusnet can’t continue to grow the way we have so far. We have got find a way to deliver a better model.
“No office closures are proposed as part of this move and investment in frontline services will continue to be treated as a priority in the coming months and years,” he added.
Under the proposals, Marc Allera will continue to be CEO of BT’s consumer division including Plusnet.
He said: “After six fantastic years leading the great team at Plusnet, Andy has decided to take a new direction and I’d like to offer my sincere thanks for all the hard work he has done for Plusnet and its customers.
“Plusnet is one of the three brilliant brands in BT’s Consumer Division.”
The proposals follow EE’s integration into BT in 2017.