(Photo: Thinkstock)

(Bloomberg) — California cities and counties will see their required contributions to the largest U.S. pension fund almost double in five years, according to an analysis by the California Policy Center.

In the fiscal year beginning in July, local payments to the California Public Employees’ Retirement System will total $5.3 billion and rise to $9.8 billion in fiscal 2023, according to the right-leaning group that examines public pensions.

— Read Abe sells Japan’s elderly on charms of country life to save economy on ThinkAdvisor.

The increase reflects Calpers’ decision in December to roll back the expected rate of return on its investments. That means the system’s 3,000 cities, counties, school districts and other public agencies will have to put more taxpayer money into the fund because they can’t count as heavily on anticipated investment income to cover future benefit checks.

Calpers hasn’t calculated the dollar impact of reducing the investment return over the years, said the group, which derived its estimate from guidance the system sent in January.

Including the costs paid by cities and counties that run their own systems, the fiscal 2018 tab will be at least $13 billion to meet retirement obligations for public workers, according to the analysis, which is based on actuarial reports and audited financial statements.

Barring any changes to pensions, “several California cities and counties will find themselves forced to slash other spending,” the group wrote in its report. “The less fortunate will simply be unable to pay the bills they receive from Calpers or their local retirement system.”

— Read Calpers braces for lower returns in ‘most challenging market’ on ThinkAdvisor.

Copyright 2018 Bloomberg. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.