The CSA and the self employed

I know this comes up a lot with regards to absent dads but I am asking from the pespective of an absent mum.
I have just had the CSA award of £5 per week based on the ex's part time earnings.
I have queried her cash in hand self employed wages and the CSA say there is little thay can do unless HMRC have her details. The CSA did say they will look a little deeper and let me know.
The question is should I go for broke now and shop her to HMRC on the basis she is trying to take me to the cleaners at a final hearing in November or wait until after the court hearing to shop her to the tax dodgers hot line so that I can get the child maintenance that I am entitled to.
Is is worth having this bargaining chip at the court?
I don't understand why some people don't realise when they are on to a good thing and just agree to an amicable settlement.

It's a good question and one I personally toy with on an almost daily basis. Stbx has his own business and whilst there is no massive tax evasion going on, I know enough and suspect more....but I am sure the HMRC would be interested.

For me, it feels a step too far to contact them. I am too loyal, I guess. Ridiculous when you think about what he's done but there you go!

However, I haven't yet had his form E and this will be interesting and may push me the other way.

I would personally hold it in hand as something of a stick to beat her with (lol!). What you know may well come in useful in negotiations. The moment to use it will probably reveal itself in time.