Part of Franklin D. Roosevelt’s New Deal included the establishment of the Social Security Administration to tax Americans in order to support retired folks, and those in need of disability pay. The administration also issues numbers for individuals that now serve as national identification. But since 1980 it has another job: maintaining the Death Master File, a database of everyone with a social security number who has died.

Sometimes, people end up on that list by mistake. For Priceonomics, Zachary Crokett writes:

In 2011, the Office of the Inspector General conducted an audit of the Death Master File, and found that, from May 2007 to April 2010, 36,657 living people (12,219 per year) had been prematurely added, nulling them legally dead. After probing deeper, officials estimated that between 700 and 2,800 people were erroneously declared dead every month since the list’s inception. Over the file's 35-year history, the Inspector General suspects that more than 500,000 Americans have been affected.

Being dead makes it very hard to do the things needed to live. Americans have been told they are actually dead while trying to get a new driver’s license, retirees have waited for checks that never came they needed to pay for vital medications and while trying to open a bank account, Crokett reports.

People who rely on their social security benefits are especially vulnerable. Blake Ellis at CNN reports on the experience of Laura Brooks, a 52-year old mother of two who was on permanent disability due to her severe depression. Ellis writes:

When she went to the Social Security office in January 2001, she found out she was declared dead on Dec. 6, 2000. To correct this, she had to submit the pay stubs she was receiving from a program that helps people on disability get back to work.

Even then it took two months and she wasn’t able to receive the disability payments she had missed while "dead."

Most of the mistakes are a simple typo created when a clerk, perhaps at the funeral home, subs one digit in a social security number for another. The error also leaves people open to identify theft because their SSN is published in the Master Death File, but it takes a few weeks for the administration to fully discontinue the number.

Ultimately it’s down to numbers. Since about 2.8 million people die each year, Crokett calculates that the error rate is less than 1 percent if about 12,000 are mistakenly marked as dead. However, the error is still frustrating to those who experience it.