About
About EstQuarterly
A free calculator that tells you how much to send the IRS each quarter to avoid the estimated-tax underpayment penalty.
For freelancers, 1099 contractors, side businesses, and investment/rental income. It computes the federal safe harbor (IRC §6654 / Form 2210 / Pub 505): the smaller of 90% of this year's tax or 100%/110% of last year's, less withholding, split into four quarters. A planning estimate, not tax advice — confirm with the IRS instructions or a professional.