NBP revised Poland's historical resale price data — old charts need checking

NBP's latest housing-market database extends the official series through the second quarter of 2026. More importantly for analysts, the central bank says historical transaction prices for the secondary market were revised retrospectively after integration of source data.

A revision is not a new price movement. It changes the estimate of what happened in earlier quarters and can therefore alter year-on-year rates, peaks, troughs and comparisons among Warsaw, Krakow, Wroclaw and other cities. Charts based on an older download may no longer reconcile with the current database.

The practical editorial rule is simple: recalculate rather than splice. Any article using long-run NBP resale prices should preserve its download date and version, then rebuild changes from the newest file. Mixing old history with the new Q2 observation can create artificial jumps.

NBP's landing page does not display a publication date for this update, so Estate Briefing records the verification date and gives the item medium confidence on timing, while treating the methodological notice itself as authoritative.

For buyers and owners, the revision matters mainly when interpreting market momentum rather than when valuing a single apartment today. A historical series is used to judge whether resale prices are accelerating, slowing or returning to an earlier peak. If the underlying observations change, those conclusions can also change even though current asking prices and completed transactions have not moved because of the revision itself. The safest approach is therefore to treat the newest NBP dataset as one internally consistent series and to recalculate every comparison from it. This is particularly important for cross-city comparisons and year-on-year changes, where relatively small revisions to earlier quarters can alter the apparent gap between markets.