Ireland’s Gross Domestic Product (GDP) data tends to be dismissed as irrelevant due to the significant distorting impact of multinational activity. The figures give little insight, at headline level, into real economic trends, which are best judged by looking at other indicators. However, the fall of 12.1 per cent in GDP in the first quarter of 2026, compared to the previous three months, as reported by the Central Statistics Office (CSO), will be the subject of some international focus. It will, for a start, have an impact on euro zone GDP figures out today, which are now likely to show a decrease for the quarter. This illustrates the enormous volatility in the international sector of the Irish economy over the past year, much of it related to the policies of US president Donald Trump. The key reason for the fall in the quarter – leaving GDP down 17.1 per cent year on year – was the massive surge in high value pharmaceutical exports from US multinational subsidiaries based in Ireland back to the American market last year. Companies were shipping product as quickly as they could back to the US to try to avoid the feared imposition of tariffs by the Trump administration. In the event, most pharmaceutical exports to the US still remain tariff free. And so shipments have fallen back sharply this year.The GDP data, as well as new US rules obliging companies to reveal where they pay tax on a country-by-country basis, combine to increase the spotlight on the way these companies use Irish subsidiaries to cut their global tax bills and the scale of their activities in Ireland. As the Irish Times reports today, many of the individual tax payments they make are enormous.These trends have already attracted attention from the Trump administration, with the US president mentioning Ireland’s role in pharma production for the US market on a number of occasions. And there are signs that new tax breaks for companies building plants back in the US and private deals done by the administration with big pharma companies are attracting investment to many American states.What this means for the Irish pharma sector remains to be seen – and there are some major new plants coming on stream in Ireland. But the remaking of supply chains driven by the Trump administration does pose some threats for Ireland.Fortunately, the detail of the CSO figures shows that growth continues in the domestic economy, despite a challenging backdrop. Separate CSO unemployment figures do show an increase last month and parts of the jobs market are having some difficulties. This will need to be watched, even if tax figures show income tax remains solid. Depending on what happens in the Gulf, Irish economic resilience may face further tests this year. And the opaque fortunes of multinational Ireland will be one part of this story.