It is not complicated, if the paying parent earns less than £156,000 gross per annum.
Find out what your entitlement is by going to the Child Maintenance calculation. Basically, the first £41,600 of gross income is 12% for one child, 16% for two children, or 19% for three or more children, with the percentages applied to the income over £41,600 a year, being 9%, 12% and 15% respectively. The actual amount then depends on how many nights the children spend with both parents and whether other children are living with the parent who does not have primary care.
Then agree with your partner the level of maintenance to be paid knowing that if you went to the Child Maintenance Service, they would enforce the figure to which you are entitled. They would take account of the HMRC(TAX) assessment of your partner’s income and would not look behind that in the majority of circumstances.
If the paying parent’s income is over £156,000 gross per annum, then speak to a lawyer.
If the children are in fee-paying school and you cannot agree the level of maintenance, nor establish your combined priorities as parents for your children, then speak to a lawyer.
Keep it simple, reach agreement, whilst being aware of the Child Maintenance Service assessment that you can go to, but try never to ask the Child Maintenance Service to collect payment of any maintenance, because the overall fee to the family will be 24% of the total maintenance paid. No fees are payable if you make a family-based arrangement. The advantage of a family-based arrangement is that it can include an agreement to share other children expenses, such as private lessons, school trips and one-off needs.