T via online platforms

Hi, I would like to submit my tax return online and would like to apply for a split-year tax treatment as well, However, the official HMRC e-platform does not allow me to submit a SA109 Form . Therefore, I need to turn to a HMRC approved 3rd party online platform to submit my tax return. Pls help clarify the following: (1) If I opt for online submission via a 3rd party paid-platform, my tax return deadline as a whole (including SA 109 and others) is Jan 31, 2024? (2) Can I submit SA 109 in paper form (by post to HMRC before Oct 31, 2022) and submit other forms via HMRC e-flatform before Jan 31, 2024? Please kindly tell. Thanks and regards

Hi KF@2023,

The whole return must be submitted together whether that be online or by paper.
Using 3rd party software to submit online still has the deadline of 31/01/24.
Paper returns have the deadline of 31/10/23.

Thank you.