A reminder before each estimated tax payment
An email before each quarterly deadline, with a suggested set-aside for the quarter, so the payment is never a surprise.
Estimated taxes are due four times a year and the dates are easy to lose. SMG Tools now emails you ahead of each one, with the set-aside the tax summary suggests for the quarter — a suggestion from your figures, not a record of what you put away — and you can switch the reminder off if your accountant handles it.