By Arionne Nettles

A big drop in energy prices pushed overall consumer inflation down 0.2 percent in September, following a 0.1 percent decline in August.

That put the year-over-year change of the consumer price index at zero, which means Social Security recipients will not get an inflation-based increase in benefits in 2016.

Government cost-of-living adjustments are based on how CPI inflation changes year-over-year in the third quarter. Twice before, in 2010 and 2011, low inflation prevented the Social Security Administration from making an upward adjustment to benefits.

“That will be especially hard on families who rely on those benefits for the bulk of their income, as the costs of rent and prescription drugs are rising much faster,” said Diane Swonk, chief economist at Mesirow Financial.

The CPI measures the price of goods and services, from apparel to delivery services.

Energy prices dropped 4.7 percent in September, the largest decline since January.

The core consumer price index, which excludes the volatile sectors of food and energy, rose 0.2 percent in September, higher than the economists’ median forecast of 0.1 percent.

Shelter costs increased 3.2 percent from the year prior and the majority of that increase came from rent.

The core CPI rose 1.9 percent in September from a year ago. The Federal Reserve has said it would like to see an annual 2 percent core inflation rate before moving to increase interest rates for the first time since 2006.

“This suggests that as soon as energy prices stop falling, overall inflation will move toward the Fed’s target more quickly than most anticipate,” economists at First Trust Advisors wrote in a research note.

Other economists placed less importance on signs of firming core inflation.

“The consumer price index is a lagging indicator of economic activity, so while the improvement in the core may provide cold comfort to policy makers, the deterioration in the pace of hiring, retail activity and industrial production are undoubtedly undermining confidence that inflation pressures are in the midst of a firm rebound,” said Carl Riccadonna and Josh Wright, economists at Bloomberg Intelligence.