My wife makes more than I do but I pay for more of the household costs including a cleaner, food (dinners, etc.) and we're about to have a child and I want to renegotiate how we break up our costs. If she just feels we don't NEED something like a nanny and I think we do - am I responsible for payinf for the 100% of the nanny's fees?

You’re married right? Why are you still about what’s hers vs what’s yours?

I believe the "modern" way of addressing split finances is to do things in an equitable fashion rather than an equal contribution.

That said, I think the discussion to be had here is bigger than the nanny. It's about sharing the financial responsibility of raising children. As someone in a very financially intertwined situation I can't wrap my brain around how to determine what the approach would be.

I wish you luck! This sounds hard to me.

Take her to brunch or coffee and bring it up as part of next week’s planning. My spouse and I don’t get much time to discuss these day-to-day things, so we block time to go for coffee. It's a good excuse to explore different coffee spots.

Lunch and dinner dates are exclusively for spending time together, not for these types of' I need to talk’ situations.

I think first need that needs to be acknowledged is to count ALL money in (as one unit) and ALL money out (also home money). Then who is paying for what will not be that challenging. Sit with your wife and list down all the income and expenses. Have a common account to put equitable share of expenses so that you both are able to see the household expenses. It would help in assessing the must-do expenses/avoidable expenses.
Its better to have to basics right before mixing the kid in this dynamic as it would just complicate the burden.

1. You should have your total living expenses (monthly bills, savings, investment plans) laid out in one lump sum. You then take the total net income of your salaries and calculate the %age you each make. Then divide your total living expenses by that percentage and again by 24 or 26 paychecks. The contribute that amount. Anything left over you should be able to spend on hats or whatever.
2. You need to sit down with your spouse and joint determine how you want to manage your life together and what your priorities are. And decide together the things that matter most. I’m with your wife - daycare is awesome and should be cheaper than a nanny. Both our kids were in daycare from the end of parental leave (we had ours backed up against each other so we both got to spend time at home on our own with the little darlings) and it’s done wonders for them.

To each their own when it comes to finances in relationships. For that reason I really believe it is something you need to sit down and discuss together. If the cost of something one wants to do, but the other doesn’t, that is also something you should talk about for now and in the future.

It's one thing to be married on paper but I can't just go to her bank account and say hey pay for the cleaner! It's more nuanced than that and while yes we are married my question here is less about the legality and more about how to approach that topic.

Okay so I would have a sit down discussion on a weekend when there is free time to really invest in the conversation uninterrupted and say that you would like to make housekeeping items more efficient and take some stress away from her having to deal with a lot of small tasks on her own. So that you would like to suggest that you add both of your names to the main bank account, or whatever it is, so that you can help to better manage the things that need to be taken care of to run a happier and more proactive household.

My other comments were not meant to address legality of marriage, as you say. I am referring to the mindset of marriage that I think is off here. Unless you have a prenuptial that states otherwise, there really is no hers and his. It is 'ours' and so I think the conversation that should occur is that you want to feel like more of a team with her and work together in unison toward the same goal of having a wonderful life together and viewing things as separate things only puts obstacles in the way of efficiency. You want to take care of her and the family you created together and her income being greater should not prevent you from actioning things on behalf of the family. If you want to agree on a certain threshold of costs that requires a discussion before purchasing that is something to consider but there must be trust established by now if you have children together.

You know your marriage best. You know why you ended up paying more, maybe you can start from whatever conversations started that.

If it happened because you made more at the time, then, start the conversation with the bills, and how it was, how the bills have grown and will grow and what the family will need.
Nanny, if you can afford it might be better, dressing the kids to drop off add an additional stress and take much time. You can suggest and make your case for nanny as well as contingency for when the nanny falls ill. Similarly, for daycare, who will do pick up, drop off, when the child is sick someone has to pick the child up, and daycare closures, how many child per teacher. These will help in your convo and final decision.

Then you can talk about how are we going to pay for this child care. What %you will each put up for this. It might make sense that she takes child care. Make sure you share as much of the info needed for the both of you to make a reasonable decision. Bills, income, no room for more, etc depending on how your marriage works.

I have split finances in my marriage too. It works for me. I am also very reasonable, so I pay much more of the things based on income.

A convo about combining finances may not make sense based on how your marriage started and stipulations you both had.

Make sure to be fair to you and to the other person.