How is CMS worked out?

[Honeymonster2]

Ex has just told me he has had a pay rise (unknown amount, but not likely to be masses higher than normal) do CMS calculate the tax year previous earnings or weekly as that's how he's paid now? It'll likely be a £15 a week difference or so, so not life changing, but still better to be in my children's lunchboxes than not. Only applied through CMS this week and oh look he's had a payrise, which I assume means it happened a while ago and he didn't tell me to avoid the extra. But that's my mind playing tricks I guess. All quite fresh...

I think they only adjust the amount if it's 25% more or less than the figure they have worked out. It is reviewed yearly based on the previous tax year unless the person paying has given new information that their pay has gone up or down.

If he had the payrise before the end of the last tax year it will be included in the calculation.