This depends on a number of factors:
Disability Allowance Disregard: You can work and earn up to €165 a week after paying PRSI without your DA payment being affected.
If you have no other means, You can earn a maximum of €442.50 per week and still keep an entitlement to the minimum personal payment of €3.
For further information contact your Community Welfare Officer or look up on www.citizensinformationboard.ie or call your local Citizens Information Centre.