Returning from overseas

If someone returns from a period spent working overseas part way through the tax year and has some UK rental income to declare, are they able to use the online self assessment service? I've seen some reference somewhere that it's not possible in this situation and that they would need to use some "commercial software". Is there any way to avoid this? I think it's a simple calculation that would be covered by the property income section of the self assessment form?

Hi CAPS
The use of commercial software is needed if you are required to complete the residence section of the tax return. as you are returning part way through the year you would probably need to complete the residence section to confirm this so you would need 3rd party software. 
Thank you.