The city of San Diego said it will have to pay $263.6 million this year into its employee pension fund, known as the San Diego City Employees Retirement System, a decrease of $11.8 million from the prior year.

The annual payment, called the actuarially determined contribution, is for the 2015 fiscal year due to be paid into SDCERS on or after July 1, 2014, the city said.

As of Sept. 30, the pension fund, which also serves employees of the San Diego Unified Port District and the San Diego County Regional Airport Authority, had total assets of $6.3 billion.

At June 30, 2013, the city’s unfunded actuarial liability was $2.2 billion, a decline of $41.6 million from June 30, 2012. The decrease is mainly due to the city’s freeze on pay increases. Other factors include a long-term pay inflation rate of 3.3 percent and better investment returns last year, the city said.

The city reported its funding ratio, or the ratio of the system’s actuarial value of assets to its actuarial liabilities, was 70.4 percent as of June 30, up from nearly 69 percent in the prior fiscal year.

For the 2013 fiscal year ended June 30, SDCERS assets earned 13.6 percent, beating its prescribed benchmark rate of 12.6 percent, and placing it in the top 17th percentile of all public pension funds as measured by the Bank of New York Mellon, the city said.