You should keep details of:
- the dates when you let out your property
- all rent you get
- any income from services you give to tenants (eg if you charge for maintenance or repairs)
- rent books, receipts, invoices and bank statements
- allowable expenses you pay to run your property (eg services you pay for such as cleaning or gardening)
There are rules about what you can and can't claim as expenses on your tax return.