State tax filing

REGARDING THE STATE E-FILING FEE:  I’m reading that some people on this message thread have said that in order to pay the lower price of $20 state e-file fee instead of the $25 fee, how can I pay it early and then hold off actually e-filing it later on ?  Next year, how would I “prepay” the state filing fee early (California).??  Thanks and blessings....