F3the Secretary of State is satisfied that the case is one which falls within one or more of the cases set out in Part I of Schedule 4B or in regulations made under that Part; and

it is F4the Secretary of State’s opinion that, in all the circumstances of the case, it would be just and equitable to agree to a variation.

must have regard, in particular, to the welfare of any child likely to be affected if F6the Secretary of State did agree to a variation; and

must, or as the case may be must not, take any prescribed factors into account, or must take them into account (or not) in prescribed circumstances.

F10the Secretary of State has insufficient information to make a decision on the application for the maintenance calculation under section 11, and therefore that F10the decision would be made under section 12(1); or

other prescribed circumstances apply.

determine the basis on which the amount of child support maintenance is to be calculated in response to the application for a maintenance calculation F12... ; and

make a decision under section 11 on that basis.