The closure of the government agency in the town has resulted in the loss of more than 350 jobs in the district.
The offices are due to close on February 28, but the last of the staff moved out today so work could be carried out to hand the building back.
About 250 staff are transferring to York, but about 100 have taken a voluntary exit scheme and are leaving. The closure of the Government agency comes after the loss of nearly 200 jobs at the nearby Northallerton Prison and hundreds of county hall jobs have been axed in recent years in the town.
The RPA announced it had taken the decision to close the offices on Alverton Court in order to save several millions of pounds over the next ten years.
A multi-agency task force set up in Northallerton to lessen the impact of the closures has now drawn up a list of proposals to revitalise the centre of North Yorkshire’s county town, which will go on public display on February 20.
The Central Northallerton Masterplan involve a range of options to create employment and provide more leisure and retail facilities in Northallerton, which will be designed to complement the High Street. It will go on display on at the Golden Lion on Northallerton High Street from 3pm until 7pm.