Tax calculation advice needed please!

Hi, I'm hoping someone can help me try to figure out whether my boyfriend is paying the correct amount of tax. He gets é15.50 per hour and gets paid at the end of every month-because he works different hours every month his pay slip is never the same. His yearly tax credit is 3808.00 and monthly is 317.34. Last month he was paid é5448.00 gross: é1417.50 was taken for tax, é304.84 was taken for PRSI, his nett pay was é3725.66. Does this sound correct for his tax? Is there a formula for him to calculate tax himself so he can keep a check on it?

Any assistance would be great!

By my calculations (which could be wrong or based on incomplete information) for last month...

Gross: €5,448

TAX

Single person standard rate band = €34K p.a. or €2,833.33 p.m. (check what it says on his statement of tax credits about his SRCOP - Standard Rate Cut Off Point)

Gross tax:

€2,833.33 @ 20% = €566.67
(€5,448 - €2,833.33) @ 41% = €2,614.67 @ 41% = €1,072.01
Total: €1,638.68

Net tax (gross tax minus tax credit)

€1,638.68 - €317.34 = €1,321.34

So I don't get the same figure as above but could be missing some info or there may be a payroll error.

PRSI

Monthly PRSI exemption (2% health levy only): €551 @ 2% = €11.02
Rest at 6% (2% health levy + 6% PRSI): €5,448 - €551 = €4,897 @ 6% = €293.82
Total: €304.84*

* If/when his cumulative annual earnings exceed the employee PRSI threshold of €48,800 then he will stop paying 4% PRSI on any earnings (assuming that he does not earn more than €100,100 in the year).