> What's crazy is that they have all this information and have already computed how much tax I owe

This is not really accurate. If you're a typical employee, IRS has a pretty good idea of your income, which is just one of the many factors that goes into calculating your tax.

In particular, the IRS doesn't independently know most of the things that could cause you to get tax deductions, like whether you got married since last year, or you moved out of your parents' house and started living on your own, or you're taking care of a child, or you had self-employment expenses, or you bought textbooks for your college classes, or you donated to charity, or you paid expensive medical bills, etc.

> the IRS doesn't independently know most of the things that could cause you to get tax deductions

The vast majority of taxpayers take the standard deduction and do not itemize, so in real practical terms this is an extremely irrelevant straw man.

(https://www.taxpolicycenter.org/briefing-book/what-standard-....)

(https://www.usatoday.com/story/money/taxes/2023/02/15/itemiz...)

To be fair, I said "how much tax I owe," not how much tax you (or others) owe.

I don't have any creative deductions. And I expect many others only have one or two "interesting" deductions to add. I haven't actually measured this but I honestly expect >95% of what I enter into my tax return is information they already have.

Do they know how much you'll spend on sales tax for a given tax year? How much you'll pay out of pocket for health expenses? Do you?

These are not "interesting", but nearly everyone has 'em, and the IRS cannot know, without bending space time, how much you'll owe because of those deductions (assuming an itemized deduction, though they're still in play either way because they can help tip the balance between taking a standard or itemized deductions).

> assuming an itemized deduction

Only 13% of all US federal tax filings each year itemize deductions. That means it would help the vast majority of filers and not harm the rest in any way whatsoever. Weird thing to be against if someone isn't misanthropic.

I was pointing out to the GP that the IRS cannot know the final amount due because of the potential for some very common types of deductions.

I wasn't disagreeing with the idea of pre-filling tax return data.

But just imagine if your starting point for your taxes was "here's 95% of your information already filled out, got anything else to add?" Wouldn't that be even easier? Nobody is saying you can't itemize if you want, but for the vast majority of taxpayers the standard deduction is a larger deduction than itemizing and far lower risk of audit.

It'd be fantastic, and I agree. I never said otherwise.

I was simply offering examples of "normal" deductions that can easily change what you owe, and how those deductions aren't as uncommon as the person I was commenting to would have you believe.

Exactly, then I should be able to see that my tax calculations include only my salary and I can fill in rest of the things to get additional deduction. Infact everyone would be able to see what IRS knows and what it doesn't and deductions taken into account etc. How is it not better?

They also don’t know about the adjusted cost basis for those RSUs sold to pay for the ordinary income tax of an RSU grant.

The liability for making a simple honest mistake is greatly overstated. In most cases the IRS sends you a letter explaining the mistake and asks you to send the additional payment (or sends you the additional refund) and if you address it in a timely manner there’s no penalty or anything.

The meme about “oh I forgot to carry the one now I’m going to jail” is just Internet hyperbole.

Often times you correct it with more paper work. One year, my foreign tax deduction didn’t get filed for some reason (I was doing my own taxes by hand and sending in the forms), so I was hit with a huge tax bill of $30k or so. Then I found out I handled my non-resident wife wrong, so amend 1040X wait for ITIN, etc…it was kind of a mess. I wound up ahead, the IRS owing me instead. They were quite courteous about it on the phone.

This is my experience as well. The IRS generally knows that mistakes happen, and they generally don't really seem interested in criminally punishing small things. Normally they assess a small penalty payment at worst, and set you up with a payment plan if you don't have the money.

They will tell you what they have. You can request your tax records including what they think you owe and what you earned.

https://www.irs.gov/individuals/get-transcript

But can I do that before I file taxes? Maybe I've misunderstood but I thought this is only available after I file taxes: https://www.irs.gov/individuals/transcript-availability

I've always wondered if there's some intentional poker going on here: if the IRS shows you your report first, and you realize they've made a mistake to your advantage, you're almost certainly less likely to report it...right?