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Information Note on Revision to Trade with Northern Ireland September 2021

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Revisions Process

Trade in goods data is revised on a continuous, rolling basis.  A large component of the monthly revisions comes from incorporation of late data received from traders which replace estimates for previous non-response. Revisions also arise where data received from a trader is found to be incorrect.

All revisions are incorporated into the latest CSO release and PX-Stat tables and submitted to Eurostat each month. Due to the continuous nature of revisions, the changes are not normally highlighted.

Changes to trade data collection following Brexit

From 1st January 2021, all trade in goods with Great Britain (excluding Northern Ireland) must be reported to Revenue’s Customs declaration systems. Prior to this, data on trade with Great Britain were collected via a combination of the Intrastat survey and VAT returns.

Under the Revised Protocol on Ireland and Northern Ireland, Northern Ireland effectively remains within the EU Single Market for the movement of goods, and trade statistics with Northern Ireland continue to be compiled from Intrastat survey data and VAT returns. As part of the new rules, separately identifiable VAT numbers for Northern Irish entities were introduced from January 2021.

This introduction of Northern Irish VAT numbers has allowed traders to identify and report trade with Northern Ireland more accurately. Previously it was not always possible to distinguish whether a UK VAT number related to a trader in Great Britain or Northern Ireland.

Identification of revisions

Where a large increase in trade with Northern Ireland was recorded since the start of 2021 the data have been queried with traders. In many cases, the increases are explained by changes to supply chains.  However, in some cases, traders reported that they had previously incorrectly reported their trading partner as Great Britain, when in fact it should have been Northern Ireland. Where errors in historical data have been identified, the data have been revised by the CSO, and incorporated on a rolling basis.

Due to the large number of companies involved in trade with Northern Ireland not all the data could be queried. The CSO has therefore used data from the larger traders in combination with the newly available Northern Ireland specific VAT data to profile and apply revisions to trade with Northern Ireland for smaller traders.

Initially the revisions described here were applied for an historical period of two years (2019-2020) to allow more accurate comparisons of Ireland’s trade with Northern Ireland before and after Brexit. Data have now also been revised for the years 2016 to 2018 to produce a longer time series.

Size of revisions to trade with Northern Ireland

Table 1 gives details of the changes to  data from 2016 to 2020.  

Table 1 Revisions to trade in goods with Northern Ireland since January 2021
Revised data Original data DifferenceRevised data Original data Difference
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