Self assessment

I am now applying for self assessment for split year treatment. I know it should related with SA109. I would like to confirm whether the online appliation system under HMRC support this form? Or i need to use the third party tax return system to apply split year treatment? Furthermore, if i use HMRC online. Why part is related with split year treatment? Thanks in advanced for your assistance.

Hi,
You need to buy third party software to complete the residence section along with the other sections you require for your tax return or you can file the whole return in paper format.
Thank you.