I See the CMS is as bad as the CSA

my miscalculation I got tax completely wrong.

However from a personal point of view

I have 3 children ( all grown up now )

The CSA wanted 25% of my wages  now lets say £200 a week after deductions £50
When one of the 3 came to live with me they allowed me £25 a week for him

So now they took 25% of £175 £43.75

So in reality I was expected to support him on £6.25 a week  ( the difference between the 2 figures )

I put a claim in for support from mother, it took over 3 years to process they decided that I should be paid £5 a week by her but she was on a protected benefit so I got £0. Even my local MP could not find out what protected benefits were.

I had a statutory reassessment made at one point they decided my income was far more than my payslips showed  ( I was employed by a large local authority ) and hit me with a bill for several thousand pounds of arrears. and an increase in payments of £150 a month.
I got my local MP involved and another assessment was done this resulted in a decrease in payments of £155 a month but due to the stupid system and even though they knew it was a mistake the decrease applied N days after the assessment was done, increases dated back to the date the assessment was started !

My second wife wasn't getting much money off her ex ( I think £3.50 a week ) for the 2 children.
The CSA said because he was self employed they had to believe the books he submitted, So we wrote and said from the figures you have given us his income is £105 a week, his mortgage is £85 leaving only £20 a week to Tax and insure his car, insure the house pay for Food TV licence etc etc surely you can see this is impossible,plus no mortgage lender would allow you a mortgage  that costs 80% of your income. 

So my wife appealed and they said they took my income into account when assessing her ability to support her 2 children. At this point I write in enclosing a copy of that letter saying as I was expected by the CSA to support her 2 children then they the CSA should make an allowance on my payments for this. The answer was a blunt no we cant take into account step children only natural children.