Developers want outline permission to build up to 287 homes and a 68-bed care home on the site south of Durrington-on-Sea Railway Station.
The homes would be split into 129 houses and 158 apartments within three or four blocks, with around 350 car parking spaces.
Access to the site would be from Barrington Road at the south-east corner.
A decision is due to be made by Worthing Borough Council’s planning committee next Wednesday (July 22).
HMRC is set to vacate the application site next year and move to its new premises at the redeveloped Teville Gate House in Worthing.
The office buildings of varied heights dating largely from the 1906s would be demolished to make way for the residential development.
Officers argue it would provide an opportunity to consolidate employment uses within the more modern Durrington Bridge House.
Illustrative layouts show the care home and apartment blocks on the eastern boundary of the site.
The apartments may come forward as either residential or retirement accommodation, according to the applicant.
Although the council has a 30 per cent affordable housing target this is unlikely to be met without significant funding from Homes England.
Officers said the proposed level of affordable housing was ‘disappointing’ but reflected the high degree of contamination on site.
The applicant also owns 0.8 hectares of land beyond the western boundary of the site and will be promoting it with other land for a commerically-led mixed use space.
According to officers: “The application offers several positive possibilities for a successful future development of the site. Work is ongoing between officer and the applicant to revise and in several cases simplify and hone development parameters in order to provide a clear framework within which a reserved matters application can follow.
“In terms of planning balance and subject to the outcome of those remaining matters, the proposal can be supported.”
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