Nottinghamshire will compete in three competitions next season following confirmation that an extended Twenty20 competition will replace plans to arrange two separate events.
The LV County Championship will be preserved in its current form with a 40 or 50 over Sunday League on the cards.
"We canvassed a wide range of opinion and everyone was behind the principle of the primacy of Test match and County Championship cricket,” said ECB Chairman Giles Clarke.
"It is important that the County Championship structure is maintained to support the England Test team.
"We all recognise that there is little appetite for Test match cricket in early May and this structure allows us to play Tests in June, July and August.
"We have also listened to the spectators and counties alike about the structure and the consensus was for Twenty20 cricket to be played in June and July with a final later in the season with the qualification matches primarily at weekends."
The new extended Twenty20 competition will comprise of North and South pools with group matches played in June and July and a finals day later in the season.