self assessment

I have submitted self assessment for my rental income tax return but I need to file a tax return for my limited company but would like to know if I can file under 1 UTR number or do I need to register separately.

Hi,
Business tax for a limited company is totally different to personal tax for an individual.  
You declare your rental income through your personal tax return, using your personal Unique Taxpayer Reference number (UTR) and a self assessment tax return (SA100).  
If you have a limited company, you need to register for a business UTR and submit a return (CT600) for your limited company using the business UTR.  
Please have a look at:
Company Tax Returns
Thankyou