SSE Retail and Npower propose to create a new company to serve their combined domestic retail customers.
The Competition and Markets Authority (CMA) will now assess whether this deal could significantly reduce competition in the supply of energy to domestic customers in the UK.
The CMA has been discussing the deal with SSE Retail and Npower since it was announced. Now that the companies have provided the information necessary to start an investigation, the CMA has launched its review.
The CMA will investigate the merger on competition grounds, in line with its merger guidance.
The deadline for the initial decision is 26 April 2018. Further details, including how interested parties can submit evidence, are available on the investigation