B form, not BE.

I checked with my accountant and LHDN staff.

As long as you have a sole prop registered to your name, you are required to file B form and list the amount of businesses you have, in this case, it's 1.

In the future, if you decide to incorp Sdn Bhd/LLP or go back to full-time employment, you'll need to close down the sole prop formally via SSM in order to switch back to BE.