The BoJ's real trade series now follows the customs data by one day
Serguey Asael Shinder2 min readThe Bank of Japan's Research and Statistics Department maintains a dataset called Developments in Real Exports and Real Imports, with the most recent charts and data file both dated 17 September 2026.
The purpose is stated plainly by the Bank: to assess export and import developments consistently with real GDP, it is useful to look at them on a real-value basis with price effects excluded. For real exports the Bank also publishes breakdowns by region and by goods, which is what allows more than a single aggregate reading.
The scheduling note is the part worth recording. For the April 2026 data onward, the series is released in principle at 4:00 p.m., one business day after the Ministry of Finance publishes its "Trade Statistics (Provisional)." The Bank notes the schedule may change, that the data may be revised retroactively — through revisions to underlying statistics, base year changes and annual revisions — and that the compilation method itself may change for the purpose of the Bank's economic assessment.
What it means
Nominal trade data and real trade data answer different questions, and in a year dominated by energy prices the difference is not academic. A nominal import bill that rises because oil is dearer looks identical in the headline to one that rises because the country is buying more, and only the deflated series separates them. For anyone reading Japan's external position while an energy shock is running, the real series is the one that describes volume.
Two cautions come from the Bank's own notes rather than from us. The retroactive revision warning is not boilerplate for a deflated series: base year changes move the whole history, so a figure quoted from this dataset should carry the vintage it was taken from. And the acknowledgement that the compilation method may change to suit the Bank's economic assessment is unusual candour — it means the series is an analytical product of the central bank, not a neutral statistical output, and it should be cited as such.
The one-business-day lag is the practical scheduling fact: the customs release sets the clock, and the real series follows it.