Dad not paid his share for college trip - advice?

[GreatOak]

DS18 is due to go on his first (and only) school/college trip to NY in December. The trip came up in January. Through txts, Dad and I agreed to split the installments between us so that we would end up paying the same amount, and DS would pay the remaining amount (he has a part-time job and has saved up, bless him).

To provide a short background, his Dad and I have long been separated: DS lives half with Dad&SM and half with me/OH. Because Dad's half-week is Mon/Tue, Wed, Thu, I still pay a large amount (over what I should) to him in child support* every month.

Anyway, I've paid my two installments, but Dad has not paid his. He missed both deadlines for his two payment installments. When he missed the first one I questioned him about it (through txts) and he fobbed with off with some guff about paying it, but the payment not registering - when I phoned the college they confirmed that this was not true: Dad hasn't paid his share. The trip is now six weeks away and there's a large outstanding balance still to pay, meaning DS might not get to go at all. Do I confront Dad again (this never ends well)? Or do I simply stop my child support payments* to Dad for a couple of months (they are not court-ordered) and pay the balance of the NY trip instead?

*I understand that I must keep paying child support until DS leaves full-time education and I'm OK with that; however, Dad doesn't pay for DS’s meals at college, buy him clothes or shoes, textbooks or college fees (I had to pay them last time). Additionally, SM asked me to contribute half the cost of DS's bus pass (which I agreed to), and I provide DS with a small allowance each month. DS lives with me for half the week and so Dad & I are equally paying for his room & board, food. I think I do all DS's washing, he seems to bring it all with him on Friday from his Dad's. Dad recently bought a brand-new Lexus so I know he's not strapped for cash. I don't feel at all inclined to simply pay the rest of the money for the trip on his Dad's behalf, without taking it back in some way... but... AIBU?

The room and board sound like it's pretty balanced, so I wouldn't pay anything going forward other that things directly to your son or the supplier.

Your ex sounds a bit hopeless tbh and this has just brought it all to light.

An 18 with a PT job can save up for a trip and his father can't? not super impressive I think

This whole set up is odd, you are being used there is no way I would be paying maintenance for a child I have 50/50.

Your son is an adult and should be talking to his dad about all of this as well.

Can you afford to pay for the rest of the trip?

I would agree that in this kind of 50/50 set up (so depending on the week he spends 3 nights with you, 4 at his dad’s, and vice versa?) maintenance shouldn’t need to be paid. And especially here where the dad has gone back on his financial commitments. I also think your ds is plenty old enough to know the gist of it, and have some say in how it’s resolved. My son is 17 and knows the basics of my financial arrangement with his dad, he turns 18 at the end of the summer term, and no maintenance will be paid past that point. We all know and are ok with that. So having that perspective, your situation does sound a bit odd.
TLDR.. it’s 50/50, he’s 18, stop the CM, pay for the trip.

If you don't already start recording when your son actually stays with you so maintenance can be reassessed. I have no problem with anyone paying the minimum when you are also paying for clothes, travel etc and its not just Adhoc payments that can't be relied upon. It sounds like your x is using you as an income stream; if so he's in for a big shock when your son goes to university.

Surely at 18 he should just pick one house to live at????? It must be awful to have to live in two houses. I'm glad my parents split up before 50/50 became the norm.

I would ask Ex for the money one more time, and give him a week to pay. If he doesn't, stop the payments immediately and use them to pay the balance of what is due for the trip.
I wouldn't start paying them again either.

Just stop paying him. Pay for the school trip, keeping paying for what already seems like more than half the expenses for your son, stop paying for your ex’s Lexus.

He’s making a mug of you and you’re letting him.

Pay for the trip but tell your son you are doing so and also explain that you are therefore stopping cm payments. This will stop dad getting in first with a different version of events. Then stop cm - sound like a really unfair set up. If you feel bad about this for whatever reason once the trip is paid for pay the money directly to your son. Your ex sounds like a cf.

It certainly seems reasonable to at least pay for the trip out of the funds you would have otherwise paid him directly.