The country's current T20 Challenge series consists of six teams but the new T20 Global League would be made up of eight city-based franchises.
"We are confident the window we have chosen will make it possible to attract top-class players," said CSA chief executive Haroon Lorgat.
CSA informed the International Cricket Council of its plans this week.
A worldwide tender has been put out by CSA and the deadline for expressions of interest is Friday, 3 March.
"Our vision is to drive the creation of a new T20 destination league  that would energise the sport of cricket in South Africa by creating a global platform for the best-in-class to perform and showcase their talent to a global audience," said CSA president Chris Nenzani.
"We have received a very favourable response to our plans from the ICC and member boards and look to their support."
Cricket South Africa is planning to launch a new Twenty20 league to be played in late 2017.