[robmaister]

This is something the IRS does directly to encourage people to file even if they can't afford to pay right then. This helps with cases like self-employment income or capital gains where you can end up owing at the end of the year even with W4 withholding for your primary income stream.

The penalty for not paying is much lower than the penalty for not filling, if you owe.

It's possible your tax prep software does their own version as a middleman, but the IRS offers it directly through the same system that quarterly estimates are paid.