The English Cricket Board has confirmed that alterations will come into force for the 2017 County Championship season.
Under the new regime, there will be eight sides in Division One and 10 in Division Two.
That means that only one team will be promoted to the top flight this term to reduce the number of counties overall.
Each club will play 14 matches instead of 16, while the Royal London One-Day Cup has also been moved to a position earlier in the calendar.
"Today's decisions follow a number of productive meetings with the chief executives and chairmen of the first-class counties. We've worked closely together, looking to improve the domestic structure for the good of the game," said ECB chairman Colin Graves.
"The changes for 2017 will be good for fans, players and our international teams. The season is easier to follow, the blocks help players focus on specific skills and there's a better balance across all three formats.
"There is a clear consensus that county cricket has to be sustainable and must support the whole game. There is an appetite for change and cricket is moving fast. We must not be left behind."
The upcoming 2016 campaign is due to get underway on April 10.
