It is hoping to lure a public service agency as the main tenant, if it gets approval for its plan.

The Canberra-based property developer has lodged a works approval, similar to a development application, to the National Capital Authority to build a 10,900-square-metre office building with basement carpark near the Parliamentary Triangle.

The proposal, located at 2 Darling Street, is stage two of Doma's plan for the former carpark. Stage one was the Little National Hotel, completed in 2015.

The six-storey building will be above a two-storey basement carpark for 161 cars, including eight accessible parking spaces and space for nine motorbikes. Retail space is proposed for the ground floor, including a 144-square-metre cafe. There will be five storeys of commercial space and about 90 bicycle parking spaces.

A driveway is proposed to be built onto Darling Street for access to the basement carpark.

Doma's general manager of development, Gavin Edgar, said Bates Smart, the architects behind the Australian embassy in Washington and Canberra's airport hotel, designed the building. It could cater for one or multiple tenants.

"This design offers future flexibility for differing workplaces and allows a high-security Commonwealth agency to also upgrade the premises to suit their security classification levels," Mr Edgar said.

"Glass curtain building facades and upper-level gardens will be complemented by a sophisticated landscaping palette to deliver a striking new architectural addition to the Barton area.

"We have paid particular attention to the interplay of the new building with the Little National Hotel, and it’s connectivity and consistency with the rest of the Realm Precinct."

The new commercial building will be the 10th office developed by Doma.

Colliers International Paul Powderly said there had been an increased demand for office space in Barton.

"This is an opportune time to prepare for the anticipated Commonwealth office demand we expect to see for high-quality office in the 2020 market in Barton," Mr Powderly said.

"Securing a large office space, particularly in a high-quality modern office building, can be
difficult in the ACT."

He said A-grade vacancy rates in popular employment hubs such as the city and Parliamentary precinct were 2.6 per cent and 0.4 per cent respectively.

Earlier this year, Doma announced it would build Little National Hotels in Sydney and Newcastle.

If approved, construction is expected to begin in the second half of 2019 and predicted to be finished late 2020.

Mr Edgar said once completed, the building was estimated to be worth more than $75 million.