In May, Governor Brown said if voters reject his tax measure, districts could shorten the school year by 15 days over a two year span.
But under a new provision in the education bill those trigger cuts would allow the elimination of 15 days in both those years.
But Jill Wynns, President of the California School Boards Association, says shortening the school year from 175 days to 160 would be a step backwards.
WYNNS: "That would just be devastating for students and for the state's future and for our goals for student achievement and trying to close the achievement gap and all the things we are supposedly doing simply can't be done by having a month less school."
A spokesman with the Governor's Finance Department says the change gives school districts a better way to deal with the magnitude of cuts if the tax measure is rejected.
The tax initiative would temporarily increase income taxes on the wealthiest Californians and increase the state sales tax.