[tzs]

They already do them for the people in question. Then when the people file the IRS compares what the person filed to what the IRS expected, and if they differ the IRS tells the person that the person made a mistake.

The near completely lack of anyone complaining that the IRS was mistaken when telling the filer that the filter had a made a mistake provides strong evidence that the IRS does in fact computes people's taxes correctly.

[anigbrowl]

I made a mistake on my tax return some years ago (in the amount of a few hundred $, I just messed up a calculation) and the IRS were very pleasant to deal with - though this was before they became so understaffed that it became impossible to get someone on the phone.

[kstrauser]

That's been my experience. I got a letter from them a couple of years ago about some claimed deductions. This is my best recollection of the call, verbatim:

Agent: You claimed healthcare expenses of $4,500. Can you prove that?

Me: Ma'am, I have 4 kids. I always max out my insurance deductible.

Agent: Hahaha, me too! I understand. OK, that's reasonable. Moving on...

It was truly that straightforward and humane. The (fortunately) few times I've ever talked to an agent, they've been pleasant, competent, and empowered to use good judgment.