The Football Association has released the step five and six allocations for 2017/18, which has confirmed an expansion to 24 teams in the Thurlow Nunn League Premier Division.
The increase means that each side will play 46 league fixtures next term, as opposed to 40 in 2016/17.
Stowmarket Town, Coggeshall Town and Haverhill Borough have all been promoted from the First Division, while Wroxham and Histon have been relegated from the Isthmian and Southern League set-ups respectively.
FC Clacton and Wivenhoe Town will also remain in the Premier Division, having been granted reprieves after finishing in the bottom three.
However, there was no such luck for bottom-placed Swaffham Town, who have been demoted.
There had also been suggestions that Saffron Walden Town were destined to move sideways into the Essex Senior League, but The Bloods look set to stay put.
Meanwhile, the First Division will consist of 21 teams following the additions of Little Oakley (Essex Senior League) and Spixworth (Almary Green Anglian Combination Premier Division).
Norwich United Reserves have been elected into the division, with Leiston Reserves spared relegation.
All of these changes require ratification from the Thurlow Nunn League executive committee.