Tesla and X CEO-turned-special government employee Elon Musk claimed to have uncovered “the biggest fraud in history” when he stumbled across more than 20 million people listed in the Social Security database as over 100 years old.

“According to the Social Security database, these are the numbers of people in each age bucket with the death field set to FALSE!” Musk posted on X late Sunday, showing a chart of ages ranging from zero to 369 years old.

“Maybe Twilight is real and there are a lot of vampires collecting Social Security,” he joked, adding that “there are FAR more ‘eligible’ social security [sic] numbers than there are citizens in the USA. This might be the biggest fraud in history.”

However, Musk’s bombshell has long been known by the Social Security Administration (SSA) watchdog, which released an audit in July 2023 showing that 18.9 million people listed as 100 years or older — but not dead — were in the database.

Only 86,000 people living in the US at the time were actually centenarians, according to the Census Bureau.

The same inspector general’s office found in a March 2015 audit that 6.5 million people with Social Security numbers but no death information were over 112 years old — despite just 35 people on the planet having reached that ripe old age.

In both audits, the inspectors general concluded that “almost none” were actually cashing Social Security checks — despite the glaring accounting errors identifying people born in 1886 and 1893 as still living, in two extreme cases.

Roughly 18.4 million uncovered in the 2023 audit had not received benefits or reported income for 50 years, meaning they were likely dead.

“We believe it likely SSA did not receive or record most of the 18.9 million individuals’ death information primarily because the individuals died decades ago — before the use of electronic death reporting,” the report states.

Around 44,000 were actually receiving benefits, with 13 of those older than 112.

The oldest living man in the world — Salustiano Sanchez-Blazquez, a 112-year-old self-taught musician, coal miner and gin rummy aficionado from western New York — had died months after the first audit began.

The audits, however, did reveal that around 531 million unique Social Security numbers are in circulation — and that “thousands” may be in use to commit identity fraud.

The 2015 audit showed about $3.1 billion in earnings reported by employers or self-employed individuals who were not the actual Social Security number holder.

Alex Nowrasteh, Cato Institute vice president for economic and social policy studies, replied to Musk’s tweet by noting that a lot of Social Security numbers for people older than age 100 were “illegal immigrants paying in, not fraudulent recipients taking out.”

“By all means, clean up SSA and mark those people as deceased. But the cost of doing so is less revenue going into Social Security,” Nowrasteh said. “Maybe that’s fine, SS should be shut down anyway, but that is a downside.”

Nowrasteh explained to The Post in a Monday phone interview that migrants were “stealing identities of people who are deceased but not marked in the Social Security system.”

Many make use of a “thriving” black market for both identity theft and identity loans — the latter of which can be obtained with just an ID and Social Security number — to be able to work in the US.

Nowrasteh and other observers believe that Musk was pulling from a Social Security list known as “Numident,” which includes every number handed out since the benefits program started in 1936.

“Some people have more than one number, occasionally because they’re committing fraud, but more usually because they’ve had fraud committed against them and they were issued a new clean number,” a former SSA employee told journalist Jesse Singal.

“[A]lso you have people who received a Social Security number and then left the US, like temporary immigrant workers,” the employee added. “But there’s a long term recognized problem with SSA’s databases not marking as dead people who have died.”

Payments to dead beneficiaries have also occurred in other federal agencies.

Under former President Joe Biden, the Pension Benefit Guarantee Corporation, a government agency, made $127 million in overpayments to a Teamsters pension fund with nearly 3,500 dead members — before reaching a settlement with the DOJ to return the funds.

The first US citizen to receive Social Security payments was Ida May Fuller, who was born in 1874, retired in 1939 and was on the government dole by January 1940. She collected $22,888.92 in benefits before her death in 1975.

SSA reps did not immediately respond to a request for comment.