Here's a couple of interesting charts from:
Actual number of audits for 2019. I couldn't find actual numbers for a more recent year but I did find percentages so you can assume the numbers of returns rise slightly each year.
Recommended Additional tax:
Looking at this chart, you see that the return per hour is highest for the $5 M+ category. But the second and third lines are for the two lowest income groups.
Percent of recommended taxes collected:
But then contrast how much of the excess ended up being collected and the rich win big time since the IRS is dealing with accounting firms rather than people who are at the lowest income levels.
And this comment from a different site pulls it together:
www.nber.org
For a taxpayer with TPI between the 90th and 99th percentiles, the deterrence-inclusive return is in excess of $12 per dollar spent on auditing. In contrast, they estimate a return of $5 for audits of taxpayers with below-median income.
That means that if you add the first two categories together and multiply by the expected $5 you get $1,795,175 per hour but if you add the other three categories together and multiply by $12 you get $332,724 per hour. But if an agent is only averaging $5 or $12 per hour, wouldn't it be cheaper to just cancel the IRS and save their salaries which have to be (fully burdened) in excess of $100 per hour???
So, interestingly, the money obtained via audit is coming from the working people (under $200 k), not the rich. That is the group that the extra 79,000 extra IRS agents with g u n s are going to audit. If you audit 100% of the $10 M + group, you get an extra $288,000 per hour. Numbers wise, there just aren't that many rich people compared to the numbers of poor people.