Track income and deductible expenses as they happen, and the set-aside amount calculates itself.
Expenses sorted into the categories your accountant asks for. Estimated quarterly payment based on your actual income to date, not last year's guess. Deadlines for all four quarters where you'll see them.
The goal is simple: never again discover in April what you should have been setting aside in June.
Who it's for: Freelancers, contractors and anyone with 1099 income who has been penalized for underpayment at least once.