The Advertising Standards Authority (ASA) had started it's own investigation, but referred them to the OFT due to the sheer volume of individual complaints. The ASA had ruled that Groupon had breached the advertising code 11 times and had a further 37 breaches settled informally.
Groupon who offer daily deals to their members ranging from meals to nail extensions has often courted controversy. Last month a baker faced closure after having to sell 100,000 cupcakes at a loss.
The main issues with the Groupon advertising were exaggerated claims on the savings made, and whether the offers were actually available.
Groupon's latest breach was only last week when the ASA banned an email promotion for cosmetic surgery, ruling that it pressurized customers to make a life-changing decision in just a few hours.
Last month Groupon listed on the New York stock exchange with a valuation of $12.7bn, however its share price has since slumped.