COLA Ledger

An independent reference — not affiliated with the Social Security Administration. Every figure traced to the government publication that produced it.

The 2018 Social Security COLA — 2.0%

Cost-of-living adjustment, 2018

2.0%

This adjustment was determined in 2017, took effect with benefits payable for December 2017, and first reached checks in January 2018.

Determined in
2017December-effective
First in a check
January 2018
Comparison quarter
Q3 2017CPI-W 239.668
Base quarter
Q3 2016CPI-W 235.057

SSA’s own table lists this adjustment under 2017, the year it was determined. The public name it by the year it reaches a check, which is one later. This site uses the name people search for. Why the two labels disagree.

The CPI-W values behind the 2.0%

Every adjustment is an average of three monthly index readings against an average of three others. These are the six values, as the Bureau of Labor Statistics published them for series CWUR0000SA0 — all items, U.S. city average, not seasonally adjusted.

CPI-W monthly index values and quarterly averages behind the 2018 adjustment
QuarterMonthCPI-W index
Base — Q3 2016July 2016234.771
August 2016234.904
September 2016235.495
Base quarter average235.057
Comparison — Q3 2017July 2017238.617
August 2017239.448
September 2017240.939
Comparison quarter average239.668

The quarterly averages are rounded to three decimal places — the precision the determination-2017 notice specifies — and the percentage increase between them is then rounded to the nearest tenth of a percentage point. That gives 2.0%.

Reproduced from the raw index

Recomputing this adjustment from the committed CPI-W series returns 2.0%, matching SSA’s published figure. That check runs on all 51 determinations as a blocking build gate, so no page here can ship a figure the arithmetic does not support.

What 2.0% did to a benefit

Monthly benefit amounts are floored to the whole dollar after the adjustment is applied, which is why these figures are not simply the percentage multiplied out.

Effect of the 2018 adjustment on two benchmark monthly benefits
Monthly benefit beforeAfter the adjustmentMonthly increaseOver a year
$1,000$1,020+$20+$240
$2,000$2,040+$40+$480

Medicare changes the answer. In 2018 the Part B standard premium was $134.00 against $134.00 the year before, so a $2,000 benefit gained +$40 gross but only +$40 net — an effective raise of 2.14% against a headline 2.0%. The full ledger for that amount.

The 2018 figures this adjustment set

Most Social Security parameters move with the adjustment or with the national average wage index. These are the committed values for 2018, each traced to the government table it came from.

Committed Social Security and Medicare parameters for 2018
Parameter2018
Maximum earnings subject to Social Security tax$128,400
SSI federal payment rate — individual$750
SSI federal payment rate — couple$1,125
Earnings needed for one Social Security credit$1,320
Retirement earnings test — under full retirement age$17,040
Retirement earnings test — year of full retirement age$45,360
Substantial gainful activity — non-blind$1,180
Substantial gainful activity — blind$1,970
Trial work period — a service month$850
First PIA bend point (eligibility at 62 this year)$895
Second PIA bend point (eligibility at 62 this year)$5,397
Medicare Part B standard monthly premium$134.00
Medicare Part B annual deductible$183

Where to go next

Sources and freshness

Figures effective December 2017. Page figures last verified against the sources above on 10 August 2026. BLS data retrieved 10 August 2026. BLS.gov cannot vouch for data or analyses derived from these data after retrieval. Corrections: the correction log · support@inventum.com.au