Update re Kazakhstan withholding tax disputes

Nostrum Oil & Gas PLC (LSE: NOG) (the "Company" and together with its subsidiaries, the "Group"), an independent oil and gas company engaging in the production, development and exploration of oil and gas in the pre-Caspian Basin of Western Kazakhstan, provides a further update on withholding tax disputes involving its principal operating subsidiary, Zhaikmunai LLP ("ZKM") and the tax authorities in the Republic of Kazakhstan ("RoK"), following on from its announcements on 3 February 2026, 9 February 2026 and 17 February 2026.

On 13 May 2026, the first instance court of the RoK informed ZKM that it had rejected ZKM's challenge to tax claims by the RoK tax authorities resulting from their tax audits of ZKM for the years 2018 and 2019.

As previously announced, the Company believes that the tax claims made by the RoK tax authorities resulting from their tax audits of ZKM for the years 2018, 2019 and 2020, which deny ZKM the benefit of relevant and valid exemptions from, or reductions to, withholding tax payable under RoK law on certain bonds issued by Group companies, remuneration on an intra-Group loan, and income from consulting services, respectively, are without merit.

Whilst the Company has not yet received the court's written judgment, the Company is extremely disappointed with the decision of the first instance court, as it believes the decision is not consistent with applicable laws. ZKM intends to appeal the first instance decision. The Company is also considering its international treaty-based remedies and will continue to defend its interests.

The Company continues to monitor developments closely and further updates will be issued as appropriate.