Income

Assalamualaikum, I have a concern regarding my monthly income.
I earn income from propery management.
80% of my income is deposited into my bank account which I pay taxes on.
20% of my income I take in cash to settle my monthly expenses no taxes paid thereon.
Please advise as to whether this is permissable.
I do try and spend atleast 5% of my monthly income in charity.

Jazakallah