The math behind raising your rates
If you raise your rate from old to new, you can lose up to 1 − old ÷ new of your billable hours and still earn exactly the same. A rise from 60 to 75 means you could lose 20% of your work with no loss of income — and you get that time back.
How to announce a rate increase
Tell clients in writing, give a clear effective date, and keep it short. You don't need to apologise; mention the value you deliver and, if you like, offer to lock in the current rate for a prepaid block of hours.