The IRS thought it wasn't allowed to withhold stimulus checks from the dead. So it paid more than 1 million of them.

The IRS sent stimulus checks to more than 1 million people who had died because it initially believed it did not have the legal authority to withhold them, according to an independent watchdog.

The administration later reversed itself, and began trying to block payments going to the dead while asking survivors to return those that did slip through, the Government Accountability Office said in an analysis released Thursday.

The report does not say what prompted the agency to reverse course, when it decided to change direction or who made the...