[chii]

> push that information to you in a customized-to-you fashion.

but the IRS somehow knows exactly what you owed them and why, so why can't they just perform that calculation before hand, and then tell you it, instead of forcing an onerous process on everyone else, and waste people's resources paying for tax-preparation services?

[sokoloff]

The largest blocker in my experience is that they don't have that information processed for 6-18 months after the filing deadline.

Source: personal experience with a period of very-late filing in my younger and dumber days.

Other factors are that they can't possibly know your total liability. They literally don't know exactly what you owe them.

Cash-based employment or trade, sales of securities purchased prior to the very recent cost-basis rules, basically anything schedule C or E (small business or rental property), etc, etc.

They might be able to auto-file something close for the simple W-2 employee case with no investments, but they don't have a secret computer system with your full return auto-prepared and just waiting to catch you for forgetting to enter $12 in bank interest from a long-forgotten account.

[ctdonath]

The IRS knows the maximum you owe. If you just want them to send you a bill and you pay it without contention, that could be arranged. If you want to use any deductions, then you'll have to work thru the paperwork explaining why you don't owe them so much.

[chrisan]

> but the IRS somehow knows exactly what you owed them and why

They know how much you owe them before deductions.