The MTA has been randomly mailing out tens of thousands of free MetroCards to handicapped riders to save money on Access-a-Ride trips– but no oversight has led to rampant abuse, according to a new report by its Inspector General.

The cash-strapped authority began sending out the Zero-Fare cards in March 2013 after the idea was proposed in a report by a Manhattan-based consultant company called McKinsey & Company as a way to save money.

Each card has four free trips a day for Access-a-Ride users, and four for a personal care attendant who would accompany the rider.

The MTA has been trying to come up with ways to save money on Access-a-Ride, since each trip provided by its contractors cost a staggering $66 per trip.

The cards were sent out regardless of whether the user knew about the program or wanted a card– making it easy for anyone in their household to abuse the free rides.

“MetroCard fraud is harmful to the system, and deprives the system of legitimate fares,” said Inspector General Barry Kluger. “At a time when every dollar is crucial, it deprives the system of much-needed revenue.”

Over 40 percent of cards that went to wheelchair-using rides were swiped at stations that weren’t accessible, the report says.

The card of one woman who uses a wheelchair was used a whopping 118 times last fall at the York Street station– which isn’t accessible.

Many users were found to be spreading the 8 trips throughout the day– making it clear they aren’t even using an aide.

Worse, some free MetroCards are even being used in the subway and bus system while the owner is actually on an Access-a-Ride van.

And the MTA has no policy or process to deactive cards being used fraudulently, according to the report.

Its own MetroCard Fraud Unit hasn’t even been hunting for fraud in the new program, the report says.

The MTA said they would create a fraud unit that would look for suspicious activity, and that efforts to save money at Access-a-Ride had saved several hundreds of millions of dollars in recent years.

The Post previously reported how the MTA has been saving money by putting Access-a-Ride customers into new handicapped-accessible taxis hitting the road.