The first phase of the investigation will assess whether the deal could reduce competition and choice, and is likely to last until 24 April 2017, the CMA said.
If the initial investigation finds that the acquisition could reduce competition, the CMA will then launch a more in-depth investigation which will last up to 24 weeks, unless the companies offer undertakings to address its concerns, it said.
Heineken announced plans with Vine Acquisitions to buy "Punch Securitisation A", made up of approximately 1,900 pubs across the UK, in December 2016, and shareholders voted in favour of the scheme on 10 February.
A Heineken spokesperson said: "This morning’s announcement confirms an important and fully expected stage in the process to finalise our acquisition of the Securitisation A pubs from Punch and Heineken will be fully cooperating with the CMA."
Heineken entered the UK pub market when it bought Scottish & Newcastle’s operations in the UK in 2008, and has invested over £20m each year since 2014 in building its Star Pubs & Bars business, it said. It currently owns 1,049 leased and tenanted pubs.
The company "considers pubs to be an integral part of British culture and that high-quality, well invested pubs run by skilled and motivated operators will continue to prosper", it said when the acquisition was announced. The purchase would make Heineken the third-largest pub business in the UK.
Competition expert Angelique Bret of Pinsent Masons, the law firm behind Out-Law.com said: "This will involve a detailed assessment by the CMA of local markets where both parties own or control pubs. The CMA will assess, in particular, where the merger could lead to a lessening of competition in a particular areas such that it would result in increased prices to consumers. This will depend on a number of factors including the type of pub, the nature of the area, the combined market shares of the parties in these areas and their geographic closeness compared to other competing pubs."
"There are a number of precedents for this analysis from previous mergers in the sector, for example the Green King and Spirit Pub merger in 2014. The parties will therefore be well prepared and will have already identified whether there are potential areas of concern. If so, they will have considered the possibility of offering to make divestments in order to avoid a lengthy, in-depth second investigation. The CMA will be keen to secure the views of competitors and customers in the context of its formal investigation," Bret said.