Twice over the last three years, I have gotten letters from the IRS claiming that I owed thousands of dollars in additional taxes. Both times, when the dust settled, the problem was the IRS's inability to apply their own instructions, or perform basic arithmetic.
In the tax code, the government has levied a duty on each of us that, in general, is impossible for us to perform. That's why there is such a thing as a "tax accountant". Now, apparently, the IRS's job has become impossible for it to perform, as well.