Ireland’s Central Statistics Office (CSO) estimated that consumer prices rose by 3.9% between September 2025 and September 2026 in its flash estimate of the Harmonised Index of Consumer Prices (HICP), published on 1 October 2026. The index was estimated to increase by 0.2% from August. The annual rate was higher than the 3.4% reported for August 2026, but September’s figure is not yet the final HICP result. The CSO explicitly said the flash estimates can be revised when final results are published the following month. The 3.9% should therefore not be treated as a settled price increase or as the rise experienced by every household in its own spending. It is a statistical estimate of average price change across a defined consumption basket.

The September components show that the headline combines subgroups moving at different speeds and sometimes in different directions. Energy prices were estimated to rise 2.9% during the month and 15.3% from September 2025. Services prices fell 0.4% month on month but rose 4.1% over the year. Non-energy industrial goods were estimated to increase 0.7% during the month and 0.9% annually. Food categories also differ according to what is included: food excluding alcohol and tobacco was unchanged in the month and up 0.3% over the year; unprocessed food rose 0.6% monthly and 1.0% annually; processed food fell 0.2% monthly but rose 0.7% annually. Food including alcohol and tobacco was unchanged in September and 0.8% higher than a year earlier. These special aggregates should not be conflated with the all-items rate.

Exclusion-based measures often described as “core” inflation also tell different stories. HICP excluding energy and unprocessed food was estimated to be 2.8% higher than a year earlier and 0.1% lower than in August. The measure excluding energy was unchanged in the month and up 2.7% annually. The index excluding energy, food, alcohol and tobacco fell 0.1% monthly and rose 3.1% over 12 months. These are distinct special aggregates in the CSO statement, not interchangeable names for one series, because each excludes a different set of items. The HICP is a weighted average price measure. An annual rate for one component alone does not show its contribution to the overall rate; that calculation requires expenditure weights and index levels. The flash statement does not provide a contribution breakdown alongside this table.

The HICP is compiled under common European Union rules to make consumer inflation comparable across member states. Ireland’s HICP uses the same basic price data as the national CPI, but the two are not identical. The CSO identifies CPI as Ireland’s official measure of inflation and says HICP is designed for cross-country comparison. HICP coverage is narrower than CPI coverage and excludes items such as mortgage interest, building materials, motor taxes, some insurance components, union subscriptions and local property tax. That difference matters when explaining why the two indicators may diverge. Both describe average price movements for a consumption basket; neither fully captures a particular household’s income, spending mix or personal cost of living.

The provisional nature of a flash estimate also has a methodological basis. The CSO’s methods note says that complete price collection and the full quality checks carried out for final results may not be finished to the same extent by the flash deadline; some prices not yet collected can be imputed. The office says flash estimates have often been close to final results historically, while warning that the gap can widen when inflation is higher. The final Irish HICP result was scheduled alongside the CSO’s September CPI release on 8 October. Eurostat’s flash estimate for the euro area, published on 2 October, was 3.2%; that is a separate geographical aggregate, not a substitute for Ireland’s rate. September figures in this report should consequently remain labelled as estimates.