When to stay under the 100k threshold and when to just accept it? - Bonus Advice

Looking for some advice on what to do with my bonus this year.

I earn £55,000 a year and I have around £100,000 bonus coming in march. I need to decide whether to put a large chunk into my pension to avoid the ‘tax trap’ but at 32 it seems early to be putting that much away.

Some background on us. We have two kids, 5 and one who is 18 months and at nursery 2 days a week, which is about £700 per month. My wife works and earns about £35,000 a year. Our main aim is to pay off the mortgage in around 8-10 years (£200,000 left).

Last year I earned about £125,000 (total inc bonus) and I decided not to put loads in the pension. We cancelled our tax free child care and benefit and had a tax bill of £4500 to pay this back.

I pay 6% into my pension using salary sacrifice and I have two company benefits, car and healthcare which is about £5-6k and I understand this comes off my income in the calculation to stay under £100k earnings. But it isn’t an exact science and I don’t want to mess it up and end up just over £100k.

Any help and advice would be great, thanks!