SA109 form for split year treatment

I would like to apply for split year treatment for FY22/23. I understand I need to submit the SA109 form by post. Then should I submit all other tax return forms together with the SA109? Or should I submit the SA109 form and then wait for some reply and then fill in the other forms online?

Hi
You need to submit the whole return together so that is the SA100 SA109 and any other relevant supplementary pages.
Thankyou.