This depends on a number of factors:
If you are getting Disability Allowance and working, income you earn up to €427 per week is not taken into account in the means test for the medical card. Before 3 December 2018, the limit was €120 per week. Disregard for Disability Allowance will change in June 2021 from €120.00 to €140.00
For further information contact your Community Welfare Officer or look up on www.citizensinformationboard.ie or call your local Citizens Information Centre.