Is CM 20% of basic income or includes extras?

I phoned CM Options and they did not have a clue. Just spoken to CSA and they said (in a scouse accent) "we look at whats paid into your bank account each month and work it out from that"
A bit hit and miss I think!

Thanks for everyones comments though and I will base it on the CM Calculator.

Sometimes it is necessary to insist on speaking to someone senior and better trained at the CSA to get questions answered correctly.

Currently any form of income which is taxable is normally taken into account. Therefore Tets is correct about car allowances. Also bonuses and commission count as pay or salary but not usually dividends paid to a director of a limited company.

If there are children living with the non-resident parent Working Tax Credit counts as income if the non-resident parent’s earnings are higher than their new partner’s earnings. If the non-resident parent and their partner’s earnings are the same, half of the Working Tax Credit is included in the child maintenance calculation. Working Tax Credit isn't counted as income if the non-resident parent earns less than their partner.