Jointly owned property

My sister and I inherited our mother's property which we have been unable to sell so are renting. I own other properties so already do an annual return to the tax office declaring income and will add my share. My sister currently has no other income to declare. How does she report her 50% share in the property and rental income?

Hi CEP,
Thank you for your question.
Whether or not your Sister would need to complete a Self-Assessment tax return to disclose her 50% of the rental income would depend on the following criteria:
Her net share of the rental income exceeds £2,500,
Her gross income exceeds £10,000 or more irrespective of any expenses to be set off.
Or if her usual abode is outside of the UK, where she would then need to register as a Non-Resident Landlord under the NRL Scheme.
If none of these criteria are met, then she may wish to disclose her rental profit/loss via PAYE by phone on 0300 200 3200, via webchat Twitter to @HMRCcustomers or letter to “PAYE and Self-Assessment, HM Revenue and Customs, BX9 1AS, United Kingdom”.
Thank you. 

Please confirm that in the above response, the Gross Income (exceeds £10,000) refers to income from all sources, not just rental income. Thank you

Hi,
Thank you for your question.  
The gross income of £10000 refers to rental income only.  
If the gross rental income exceeds £10000, irrespective of any expenses to be set off, then a Self Assessment return will be required. 
Thank you.

Thank you for the clarification, most helpful.