If you go self employed then you will retain against that self-employment any unused tax credits that you have. One small thing is the PAYE credit of €1,830 which is only available against PAYE employments. You will still get the benefit of that but only to the extent of the PAYE employment. So as long as the PAYE employment generated at least €9,150 ( €1,830 x 5 , the 5 being to aco**** for it at 20% tax ) then you'd still get the full amount for the year. Your other credits and cut-off would be available as normal.