Context: I've heard from a couple people that if you owe a significant amount of taxes to the IRS (say several thousand dollars) at tax time, then the IRS will require you to start paying future taxes in quarterly amounts. Interestingly, this requirement was not mentioned when I did my taxes via TurboTax, despite owing quite a bit.
Question: Must I pay quarterly in the future, or is the quarterly payment plan only an option? (and FWIW, I've adjusted my W4 so this doesn't happen again).