The IRS makes tens of billions in revenue annually from penalties alone for what they deem is an underpayment. If the process were not adversarial, the IRS woul

The IRS makes tens of billions in revenue annually from penalties alone for what they deem is an underpayment. If the process were not adversarial, the IRS would not be able to assess penalties for underpayments so this revenue stream would presumably be diminished. Another explanation for the adversarial tax filing process is that it is beneficial to the IRS for it to be this way https://www.irs.gov/statistics/collections-activities-penalties-and-appeals https://www.irs.gov/statistics/collections-activities-penalt...