WASCO, Calif. -- In California, a child can start kindergarten as young as 4 years old, but a new bill would require that kids be 5 by Sept. 1 of that school year.

The bill by Sen. Joe Simitan, D-Palo Alto could save the state an estimated $700 million per year by cutting enrollment. The state Department of Education says about 100,000 of the state’s 430,000 children start kindergarten before their 5th birthday.

SB 1381 is supported by policy experts and education advocates across the state including, the California PTA and the Governors Committee on Education. They argue that children under 5 are less academically and socially prepared.

“They are not ready to understand what letters are. They come in barely holding pencils sometimes, and they just aren’t mature enough to start kindergarten at that age,” said Susan Hornsby, a kindergarten teacher from Karl Clemens Elementary School in Wasco.

But some parents at Karl Clemens believe 4-year-olds can get a head start. “Four is better I think because my granddaughter started at 4 and now she is reading a lot better,” said Angel Ruiz.

The bill has been sent to the governor for his signature.

If signed, the change would take effect starting the 2012-2013 school year.