The IRS shifted around substantial resources and manpower to implement the Affordable Care Act while its overall operations and taxpayer assistance suffered, according to a Republican staff report released by the House Ways and Means committee.

The findings, released Wednesday (April 22), follow a stressful tax season for the Treasury Department, as it handled nearly 1 million people who received incorrect 1095-A forms that used the wrong data to calculate health insurance exchange enrollees’ subsidies due to a technological code glitch. Taxpayers were told they owed or were owed the wrong amount for their tax return; the IRS said those affected did not have to refile if they had already done so.

“To date, the IRS has spent over $1.2 billion on implementation of the ACA,” the report says. “In fiscal year 2014, the IRS spent $386.6 million on the ACA, including $12.1 million from the taxpayer-services account and $185.7 million from its user-fee account.”