The still-growing NBN Co has been named as the major tenant of a new 35-level tower building now under construction at 100 Mount Street, North Sydney.

But it will be late 2019– just a year before the NBN rollout is scheduled to be complete – before the NBN team can move in.

NBN Co has reportedly leased some 30,000-odd square metres of office space, about 48 percent of the building, making it the No 1 tenant.

The new arrangement will see NBN Co move out of five existing office spaces across the North Sydney landscape, including 100 Arthur Street, where it has several floors.

Next question; will the NBN builder also get the right to erect a massive signboard atop the new building, common practice among high-level North Sydney renters.

Separately, SAP Australia has also booked itself into new digs, announcing it has taken a 600 sq m space in a $1 billion tower at One Denison St, North Sydney. It will move out of its current HQ in Walker Street once that lease expires.