Hi,
The application form CF411A is the correct form to transfer NI credits between parents providing the main recipient of child benefit will not be at a loss. If you have applied to move the credits for the 2023 to 2024 tax year, you are correct that the time limits are 5 April 2025.
Please reply to the letter through the mandatory reconsideration process, it can be from yourself. Please include your wife’s details on the reconsideration letter also, with the letter marked reconsideration.
You can check the timescales for a reply here:
Check when you can expect a reply from HMRC
If you are moving credits on a regular basis you may want to contact the Child Benefit team to discuss moving the claim/credits over to the other parent to prevent completing a form for each tax year.
Child Benefit: general enquiries
Thank you.