The projections come as the Assembly Appropriations Committee prepares to consider on Friday whether the state can afford the bill named after 17-year-old Chelsea King. Convicted child molester John Albert Gardner III was sentenced to life in prison this month after pleading guilty to raping and murdering King and 14-year-old Amber Dubois in San Diego County.
Assemblyman Nathan Fletcher, R-San Diego, said AB1844, nicknamed Chelsea's Law, would have a relatively low cost for the first decade. He said it is worth the money to protect children.
The annual cost would top $1 million in 2015, $9 million by 2020, and $54 million by 2030, according to the California Department of Corrections and Rehabilitation.
It would add nearly 400 inmates and increase the number of parolees by more than 7,300 by 2030, the department projects.
"We would consider this to be a conservative estimate," Jay Atkinson, chief of the department's Offender Information Services Branch, said Saturday. "The impact won't truly be seen until way far out in the future."
The legislative analyst said increasing penalties would cost "at least a few tens of millions of dollars annually within the next decade" and "at least in the low hundreds of millions of dollars annually after several decades."
Backers, who include Republican Gov. Arnold Schwarzenegger and Democratic Assembly Speaker John Perez, have not suggested any funding source beyond taking the money from the existing state budget, which faces a $19 billion deficit this year.
"There's virtually no cost for a decade," said Fletcher. "If you look at a budget that annually exceeds $100 billion a year, that's a small price to pay to protect our children."
His bill would allow life sentences for a first offense of forcible sex crimes involving a child under 18, up from the current 15-year to 25-year sentence. The life term would be reserved for cases with aggravating factors that include kidnapping, using a weapon, torture, binding or drugging a victim or a previous sex crime conviction.
It would double sentences for some other sex crimes involving children and double parole to 10 years for felons released after serving sentences for forcible sex crimes.
The bill also would require the state to use GPS tracking for lifetime monitoring of those convicted of forcible sex crimes against children under 14. Currently, most tracking ends when offenders leave parole, despite an existing state lifetime monitoring law.
It would ban sex offenders from parks, going beyond the state law that already limits how close offenders can live to schools and parks.
The Assembly analysis suggests deleting provisions that could potentially send offenders to prison for life for inflicting a bruise during a sex crime, or subject them to lifetime parole for acts that could include touching a child over his or her clothing. That would cut the bill's costs substantially, the analysis said.
"I think it's undeniable there are significant costs," said Sen. Mark Leno, D-San Francisco, who chairs the Senate Public Safety Committee. "It's clearly a very important issue, a highly emotional issue, and we need to be grounding ourselves in fact."
Fletcher said he is open to minor changes. But he said backers will go to voters with an initiative before they accept major amendments.