Increasing Part-time working hours

I wonder if anyone could help - I currently work 16 hours per week & don't have any personal prsi as I earn under €352 per week. I have been offered an extra 4 hours per week, which would bring me over the €352. My question is simple - is it worth my while to do the extra hours or would I be losing out?

You will have an extra €14.08 in PRSI to pay so if you earn more than that then you are better off.

Thanks Joe 90 I'll check it out, but before tax & deductions I get about €19.50 an hour, so it could be worth it. I'm also trying to think ahead to my pension - in about 12 years time (unless they change the pension age again), so maybe I would be better off.