Mixed bag. - Description says it will only require permissions to access your name and email but installation requires granting access to all Sheets documents you own. Then you need to enable the app in sheets, and then again enable it in each document you want to use it in. - Does not provide insight into the formulas used so you are unable to verify the calculations are correct. - Does not appear to account for the standard deduction. This is reasonable but it should be stated in the documentation. - Would be more useful for retirement planning purposes if you had a reverse tax function to allow you to say "I want $100,000 in after-tax money from my traditional IRA. How big of a withdrawal allows this?" or stated another way, "How much do I have to earn to take home $100,000?"

This was helpful for doing a rough self-employment estimated tax payment calculation, instead of hamfisting in an arbitrary % rate.

Doesn't work. Formula doesn't show up after typing "=tax.." in a cell.