The issue is that the IRS has 7 years to audit a tax return, and since taxes are due at the time you receive the income, the interest is backdated if you happen to underpay taxes and it compounds. So if they audited your 2019 return today and you underpaid $1k, you’d owe $1333 today with compound interest over those 6 years.
Small oops mistakes, I've never heard of someone being charged criminally.
BIG "yeah that was intentional" kinda obvious under-reporting of income, that turns into charges at times.
I actually had a big misunderstanding in terms of amounts once where the IRS thought I cashed out a large 401k. They simply sent me a letter and we mailed back and forth and I showed them that in fact I didn't cash it out and it just moved and it was all good.
The OP of the currently highest voted HN comment thread on this news article, for one:
> Me: What if I get it wrong?
> Gov’t: You go to prison
EDIT: Ok, I'm not from the US and for some reason I was under the impression that incorrect tax returns were punishable crimes. I guess some movie I watched as a kid impressed that notion and it was never challenged until now.