After reading this, I did decide to up by $10, I charge by time. It has been 2 years since my last increase but I do charge extra for any tax credit work, i.e. Form 8867. The increase is small but my costs have hardly increased. The slight bit for the software but Verifyle is still the same as is my insurance. I make enough and work as much as I wish. It's been wonderful since relinquishing bookkeeping, payroll, and virtually all small businesses - just a couple of small SMLLC's and a couple with rentals. I'm okay and I know some of my clients don't have a lot extra.
Gail, do work less. Your time and mental and physical health are so much more important. Charge more, work less with the remaining better clients. It seems to work with lots of folks.