How will my bonuses be taxed?

bjones43

I'm in need of some advice so I can plan my finances next year.
I have a job with a yearly income of around £51,500 (£4350 before tax/NI/deductions, £3250 after) I make salary sacrifice contributions of 6%. 

I'm now due to receive three bonuses a year, which will push me into the higher tax bracket and make planning more complicated. I will receive two of these bonuses in one in my March PAYE and this will be an additional £16k. (My 11 months cumulative taxable amount is currently £43600).

I think I can figure out what will happen in March, and I will look to increase my pension contribution to minimise the higher rate of tax due.

Next tax year my bonuses will come into my PAYE in April, September and January. I'm struggling to find out how my tax will be worked out in my monthly pay, as for 9 months before pension contributions/tax it will be around £4300, and then for the other 3 it will be around £13000. 

Also, my work have said they wouldn't be prepared to change my pension contributions regularly, but could change it potentially once or twice during the year, so I need to try and get this right.

Can anyone either advise, or point me in the direction of a useful calculator website?


Many thanks