Remember, you don't have to reveal anything you're not comfortable with to the hiring manager. You can answer this question indirectly by giving the interviewer a range you're expecting.
Liz Ryan, CEO of consulting firm The Human Workplace, writes in a LinkedIn post, "When we call the plumber because our tub drain is clogged, we don't ask, 'What did you charge the guy down the block to unclog his drain last week?' If we do, the plumber is going to say, 'My rate is $95 an hour. Do you want me to come over or not?'"
She suggests responding to this salary question with "In this job search, I'm looking for jobs in the $95,000 to $100,000 range. Is that in the ballpark?"
The best way to prepare for this question is to figure out how much salary you want to be paid. Here's how.