Child maintenance self employed ex

[Nobu32]

Have name changed for this.

I stupidly gave up my rented house and moved into my now ex’s home (which he owns) with my dc from previous r.ship to another village away from friends and family.
Fell pregnant, fast forward 3 years later relationship broke down and he asked us to leave.
I had to start from scratch again and if it wasn’t for the help of my family and friends I really don’t know where I’d be.
In a much better place now 1.5 years on.
I’m renting again and have managed to make it a nice home over time on a low income.
Ex is a self employed high earner.
Up until recently ex was paying £80 a week child maintenance.
Since learning I have met someone new he has kicked off, been bombarding me with msgs saying he made a mistake and wants me back promising me the world etc, which I obviously declined .
He now has decreased child maintenance without warning to £60 as it’s the only thing he can control now.
Im unsure what to as I’m aware self employed people can fiddle the books and I could end up with a lot less going through CSA
Has anyone got any advice what to do? I heavily rely on child maintenance as I’m on minimum wage.

Hi there. Bit of background - am a step mums my husband is self employed as am I. His ex after a breakup decided to make up lies to involve the FIU to try to get my wage taken into account also. 3 years later tribunals etc husband paid compensation by CMS due to their poor handling of the case and the true original assessment reinstated. So tread carefully with them. Freedom of info requests showed they lead his ex down the garden path thinking she'd get a big sum of money and they get a nice cut if they could put him on collect and pay, it's created disharmony, and damaged the family after 10 years of things bumbling along prior.

From the experienced described above this is just my opinion and advice to get what's fair.
You can put his salary into the online calculator to see what he should be paying. Or pay £20 to the CMS who will pull his info from HMRC to make an assessment and this can be paid directly from him to your account. If he is self employed via a Ltd company his accountant will have structured things tax efficiently and the CMS system will automatically only take into account his basic PAYE salary. When that happens the letter will tell you how long you have to do a mandatory reconsideration (think it's 30 days) and you can ask them to do a variation to take into account any other income such as dividends which is how much self employed Ltd company people structure their income. Depending what he is like as a person you could either go through the above process step by step if he messes you about OR you could show your cards so to speak to indicate you know the process and will go down that route if he decides not to be fair and just provide details of his PAYE income and dividends to sort out a private arrangement. Private arrangement is the way to go - you'll have nothing but hassle via the CMS whether your paying or receiving parent. But it's useful to know their process should you need it if he insists on being a d@@@. Good luck with it .