Hi Julius
Not familiar with Self employed but with ordinary new employees to any firm the process is usually;
For the first 4 weeksemergancy tax with reduced token tax credit of I think €30'
then no tax credit for next four weeks and
after week 8, all income taxed at higher rate of 41%.
This is so new employees get their butts in gear and get tax cert to new employer asap. Tax office's are usually grand and very quick with issuing certs so give them a call.
Also if there is an issue with your previous employment or tax history, they will usually issue you with a Week 1 Cert, which just means that tax credits are not cumulative but on a week by week basis, any overpayment can be reclaimed after the year end.
And id agree with Niceoneted, stay as an employee if you can.
Hope that was clearer than mud