11.—(1) Where an application has been made under section 4 or 7 of the 1991 Act the Secretary of State must, as soon as reasonably practicable, give written notice to the non-resident parent—
(a)requesting such information as the Secretary of State may require to make the maintenance calculation; and
(b)where relevant, advising the non-resident parent of the power of the Secretary of State to make an estimate of income or a default maintenance decision.
(2) The notice must be sent by post to the last known address of the non-resident parent.