Supplementary Welfare Allowance(SWA) is a means-tested scheme, based on the means at the time of application. Having been self-employed is not of itself a bar to applying for SWA.
Self-employed people who are no longer in business may also qualify for Jobseeker's Allowance (also means-tested). They do not qualify for Jobseeker's Benefit (PRSI-based) as the Class S contributions paid by the self-employed does not entitle a payee to Jobseeker's Benefit.
If there is another income in the household (e.g. person was employed or self-employed and is now unemployed, partner/spouse in full time employment), the unemployed person may not qualify for Jobseeker's or SWA based on means.