You do not have to be in pensionable employment to contribute to a PRSA.
The Pensions Board have a document called [broken link removed] which is helpful.
It states "PRSAs are available to you regardless of your job or employment status. You can get a PRSA if you are a part-time or casual employee, a highly paid professional, self-employed, a homemaker, a carer, a jobseeker, a contractor, an employer, an employee or a partner in a partnership.
You can continue to contribute to a PRSA after you retire, as long
as you are not aged 75 or over."