Earlier this month, the price comparison site revealed that is was to acquire MoneySavingExpert for £87m.
MoneySavingExpert was established in 2003 by personal finance journalist Martin Lewis.
Lewis will become an employee of the MoneySupermarket.com group once the deal is completed and will be editor-in-chief of MoneySavingExpert.
A £35m upfront cash payment will be made as part of the deal alongside approximately 22.1m MoneySupermarket.com shares. There is also a deferred consideration of up to £27m subject to performance.
The deal is set to be concluded in September or October and is subject to MoneySupermarket.com shareholder approval.
The OFT is considering whether arrangements are in progress or in contemplation which, if carried into effect, will result in the creation of a relevant merger situation under the merger provisions of the Enterprise Act 2002 and, if so, whether the creation of that situation may be expected to result in a substantial lessening of competition within any market or markets in the UK.