I think my broker deducts short-option liabilities from the cash which is eligible for interest

I'm curious, if you were short brk, are you saying you sold more calls than you had shares to back? Or were the calls sold against long dated calls you are holding that may require a broker to view it differently due to the mismatch of expiration timing? Or is it something completely different I'm not even considering?

In my particular case I only sold pure covered calls where I had shares to back them. All my cash has been earning a nice bit of interest. In hindsight I should have sold enough to cover all my shares but perfection is rarely attainable.

I usually have a mixture of shares and long dated calls so I'm interested in how you view the various exposures. It just so happens I only have shares and covered calls currently because I closed out all of my long dated call positions during the high valuations back in August. I'm always interested in other strategies from those willing to share.

Jeff