When ex changed jobs to a better rate of pay CSA wouldn't change a thing without my actioning it. They only cared in a decrease in pay rate from his side of things. He was told that he could not put in place an estimate based on increased earnings. I rang to confirm this. So we have been living on a $0 assessment for this financial year waiting for the new tax to trigger a new assessment. I could have asked for a COA to have his income reflected more accurately (I think that's what his other ex did) but I refuse to divulge my information with no protection in place for recourse, so I didn't. Plus this way his not paying the set amount affects nothing, I don't get decreased FTB based on an amount that he isn't going pay anyway.

ETA and yes, I believe unless you challenge the new assessment that will be triggered at tax time, the new assessment will be based on his previous year of little to no work, so a smaller amount than what it would be based on his working for the year. You can challenge that though, not quite sure on the procedure as I never bothered given the above reasons. I've only ever challenged an estimate.