Earlier in the month, experts suggested that Nigeria’s headline inflation for December was projected to more than double, going from 14.5% in November to 31.2%.
However, according to the country’s National Bureau of Statistics (NBS), Nigeria’s inflation rate rose slightly to 15.15 per cent in December 2025, after some alteration in the computation methodology of its consumer price index.
“In Nigeria, the National Bureau of Statistics (NBS) recently rebased the CPI to replace outgoing reference periods (2009),” the NBS stated on its website.
“Rebasing aligns the price and weight reference periods with the current economic environment, ensuring methodological accuracy, updating the composition of the goods and services basket, revising item weights, and incorporating necessary improvements,” it added.
The National Bureau of Statistics disclosed that the Consumer Price Index (CPI) rose to 131.2 points last month from 130.5 points in November, signifying a decelerated rate of increase in average prices.
Year-over-year, inflation decreased from 17.33 percent in November 2025 to 34.80 percent in December 2024, which denotes a significant deceleration in headline inflation over the previous fiscal year.
“On a year-on-year basis, the December Headline inflation rate was 19.65% lower than the rate recorded in December 2024 (34.80%).
This shows that the Headline inflation rate (year-on-year basis) decreased in December 2025 compared to the same month in the preceding year (i.e., December 2024), though with a different base year, November 2009 = 100,” the NBS revealed in its report.
“On a month-on-month basis, the Headline inflation rate in December 2025 was 0.54%, which is 0.69% less than the rate recorded in November 2025 (1.22%).
This means that in December 2025, the rate of increase in the average price level was lower than in November 2025,” it added.
While the decrease registered in the year-on-year inflation should be a cause for celebration, it raises some questions, particularly on the effects of rebasing.
Contention surrounding Nigeria’s decision to rebase its CPI
Earlier in the week, during a virtual stakeholders engagement hosted by Nigeria’s National Bureau of Statistics (NBS) and the Nigerian Economic Summit Group (NESG), Adeyemi Adeniran, CEO of the NBS, disclosed that the group will ‘normalise’ the country’s inflation figures for the previous month.
“Following the rebasing exercise and the methodology adopted for December 2025, a significant artificial spike in the inflation rate is expected, as some analysts have already projected.
This spike arises from the base effect, with December 2024 equated to 100 following the rebasing,” he said.
“Base effects are common in statistical practice, particularly when comparing data across periods with unusually high or low prices. They are neither unexpected nor unusual.
However, when such effects occur, especially when they are artificial and arithmetic rather than reflective of structural changes in the economy, it is essential to clearly communicate and explain them to users,” he added.
This idea brought about some concern for several economists and experts, as they raised the question of credibility and transparency, as to whether the NBS can decide to simply change how it computes the country’s inflation figures.
They worry if the figures would accurately represent the economic reality of the common Nigerian.
However, as reported by Nairametrics, the International Monetary Fund has endorsed Nigeria’s rebasing idea.
“We welcome the December Consumer Price Index inflation figures released by the Nigerian Bureau of Statistics, which show an easing of inflation that, if sustained, will help reduce cost-of-living pressures and support macroeconomic stability,” the global lender disclosed in a statement issued on Thursday on behalf of the IMF Resident Representative for Nigeria, Christian Ebeke.
“The release reflects a welcome change in methodology that aligns Nigeria’s CPI calculation with international best practices, as set out by ECOWAS and the IMF’s 2020 CPI Manual,” the statement added.
