Proof of living in the UK for Self Employed

Hello,

I am doing the Citizenship online application and I have been requested to provide the following:

"Proof of living in the UK " If you are an EEA National, you need to include letters from employers, educational establishments, or other Government Departments indicating your presence in the United Kingdom during the relevant period.

Bank statements or household bills are not suitable proof you have been living in the UK.

So no bank statements, household bills can be of use - and I am Self employed (not employed and not a student) So what documents can be as proof and the relevant period that means? I have already the Permanent Residency card.

Any thoughts?

Best Wishes!