Statistics Bureau Reviews Inflation Data Standards Amid 31% December Spike Forecast

The  National Bureau of Statistics (NBS) has said will change the way it calculates inflation as last year’s rebasing measure could make December’s year-on-year inflation appear artificially high, the agency said on Tuesday.

Ahead of the December consumer price index data release this week, analysts say they expect a disruption in the disinflation trend recorded in the country.

December inflation data is due to be published on Thursday. Analysts are predicting a sharp rise in the headline figure to over 30 per cent from 14.45 per cent year-on-year in November.

“The widely reported 30 per cent figure for December is only a projection and not from the bureau,” said Ayo Anthony, head of prices at NBS. Consumer inflation peaked near 35 per cent in December 2024 before falling sharply after the statistics office revised its base year and as food prices eased.

“This spike is not the real inflation rate; it is an artificial spike caused by the base effect from rebasing,” Anthony said. “We are removing the single-month index reference period and replacing it with a 12-month reference period for 2024 to report actual inflation.”

Anthony noted that while countries like South Africa and Kenya use a one-month base, Nigeria’s sharp price increases make that method unsuitable. Prior to last year’s rebasing, Nigeria rebased its inflation data in 2009.

“We haven’t rebased in 15 years, so some of the base effect playing out is due to that lag,” said Bonaventure Nwosu, head of communications at NBS. “Whatever spike you see for December is a one-off and should not be interpreted as real inflation. From January 2026, figures will normalize and reflect actual market conditions.”

The bureau said the new methodology will provide a clearer picture of inflationary pressures in Africa’s most populous nation.

They argued that the base effect is expected to push the December figure higher.

Analysts at Afrinvest West Africa and Financial Derivatives Company say they expect the December inflation figure to rise to between 30 and 33 per cent from 14.5 per cent that was recorded in November 2025 due to the effects of the rebasing.

The NBS is expected to release the December inflation figures on January 15.

“Nigeria’s inflation rate is expected to spike to 30.5 per cent in December from 14.45 per cent in November, due to a correctional base year effect,” analysts at FDC said.

Nigeria had recorded eight consecutive months of disinflation between April and November 2025. Over this period, the headline inflation rate had declined steadily from 24.2 per cent year on year in March to 14.5 per cent in November.

This marked the lowest level since the CPI rebasing in December 2024 and the softest inflation outcome since October 2020 when it was at 14.2 per cent, under the previous CPI framework.

Analysts at Afrinvest noted that the “December 2024 rebasing materially altered the CPI structure. The weights of food & non-alcoholic beverages and energy declined to 40.1 per cent and 6.4 per cent from 51.8 per cent and 10.8 per cent, respectively, while the core component, which captures the price dynamics of less volatile items, expanded to 53.5 per cent from 37.4 per cent. This structural shift partly explains the pronounced disinflation observed through most of 2025, even when market prices of major staples and consumer necessities remained sticky.

“Based on our model, which benchmarks December 2025 price dynamics against the rebased CPI baseline of December 2024, we estimate headline inflation to rise sharply to 33.6 per cent y/y from 14.5 per cent in November, driven largely by base effects. On a m/m basis, headline inflation is estimated at 2.4 per cent from 1.2 per cent in November, representing the strongest monthly increase since March 2025 when it was 3.9 per cent.”

Both food and core components are expected to contribute to the projected uptick. Food inflation is estimated to rise by 2.7 per cent m/m, compared to 1.1 per cent in November, with the y/y rate jumping to 31.7 per cent from 11.1 per cent, reflecting base effects and typical year-end demand pressures on staples and frozen foods.

Core inflation is estimated at 1.9 per cent m/m from 1.3 per cent in November, with the y/y rate rising to 34.5 per cent from 18.0 per cent, also largely driven by base effects. Overall, we estimate Nigeria’s average headline inflation rate for 2025 at 22.1 per cent (FG’s budget baseline 15.8 per cent), although, we anticipate the average print to correct downward to 15.4 per cent in 2026 on the support of relative exchange rate stability and statistical realignment.