If you’re running a property rental business with profits of more than £5,965, you’ll also need to pay Class 2 National Insurance. If your profits are less than this, you can make voluntary National Insurance payments that will enable you to claim the full State Pension.
You’re only considered to be running a property business if you meet all three of these criteria:
Your main job is being a landlord
You let more than one property
You buy property specifically to rent out