What's reasonable if I'm the breadwinner?

[threewords3]

I'm the main wage earner (and always have been).
We have a 4 year old together, plus at present I currently contribute to the payments exH makes to his daughter from a previous relationship.
Once his financial situation is a little more secure I have said that I will stop contributing to his daughters maintenance. I'm wondering whether I should expect him to contribute towards our son on a regular basis? At present he gives me 50% of specific extra costs but I cover all day to day expenses.
Its currently a very amicable separation and I'm most concerned that it stays that way, more than arguing over money, but equally I don't want to be taken for a mug!
Thanks

Presuming you're having 50/50 residency then I'm not sure why he would be.

sounds quite complex though so I suppose you will have to look at a lot of figures. If you're using a lawyer then there are some that specialise in financial aspects.

He has two children. He should contribute to two children. Why on earth were you contributing to his daughter's maintenance? Surely it's based on his income?

I was contributing because our finances were all joint, so the money for her came out of both of our earnings. This is still the case at the moment. (Although its vaguely complicated as those earnings are investments, not our individual salaries which are obviously not joint now weve separated). It's not quite 50/50 custody, but almost, so maybe he should not contribute more than he currently does. I'm fine with that, just wondered what was normal, as most posts on here are based on the view of the mother earning less than than the father.

If it's almost 50:50 custody and you earn more, then maybe it would be easier for you both to remain independent, so your money is for you and your child; his money is for him and his children. That will make things a lot easier. Perhaps you could agree that if there was anything over a certain amount needed, eg for a school trip, then you would split it? You could also do something like he pays for school meals and you buy the clothes. That would be easier for him as it's a set amount of money per week, nothing unexpected, with holidays where he doesn't have to pay.

It always seems to me that you and your exP have to work out together what is most appropriate based on your relationship, your custody arrangements and your financial options.

In your situation, if I understand it correctly, you have more or less 50% custody. In which case broadly speaking I'd say that you each are responsible for the children's costs when the children are with you. In terms of extras, that would be agreed according to what you both think is fair.

Having said that, if DH and I split (we have no plans - are super happy), I would expect that I would have to pay some of his share too as he wouldn't be able to afford to keep himself and the children when they were with him. As the main breadwinner and having had him as SAHD, that would be a natural assumption for me.

If it's amicable, I'd honestly say try to avoid worrying about being taken for a mug. If you're both happy with the arrangement and it's not causing any significant financial hardship, then surely that's the best solution as the less tension there is, the happier everyone, especially the DC, will be.

Thanks all.