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 announcement on 3 February 2026.

At a hearing on 6 February 2026 regarding ZKM's challenge to tax claims by the RoK tax authorities resulting from their tax audits of ZKM for the years 2018 and 2019, the RoK Ministry of Finance Appeal Board (the "Appeal Board") postponed its decision. ZKM understands that the Appeal Board is reviewing and considering communications from the Dutch tax authority pursuant to the mutual agreement procedure ("MAP") under the relevant double tax treaty between the Kingdom of the Netherlands and the RoK (the "RoK-NL Treaty") in respect of the pertinent claims, which may result in the suspension of the appeal pending the outcome of the MAP.

Paragraph 3 of Article 4 of the RoK Constitution provides that international treaties ratified by the RoK (such as the RoK-NL Treaty) have priority over RoK domestic laws (including the RoK tax code) and RoK Supreme Court precedent provides that where an international treaty contains a mutual agreement procedure such as the MAP, for the good faith performance of the treaty such mutual agreement procedure, when invoked, should be conducted between the competent authorities of the two states party to the treaty to achieve the goals of such treaty. A treaty party may not invoke the provisions of its internal law as justification for a failure to perform its treaty obligations.

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.

The Company continues to monitor developments closely and will continue to defend its interests and to assess all available legal and treaty-based remedies.

Further updates will be issued as appropriate.