6278 TSMT: Subsidiary Announces Phase II Factory Expansion in Vietnam

Release Date: July 15, 2026 Statement Date: July 14, 2026 Statement Time: 16:32:35 Company Code: 6278 Company Name: TSMT Subject: Announcement of Phase II Factory Expansion by Subsidiary TSMT Vietnam Co., Ltd. Applicable Clause: Clause 20 Event Date: July 13, 2026

Details: 1. Type of Contract: Factory Construction Project Contract 2. Event Date: November 28, 2025 – July 13, 2026 3. Board Approval Date: Not applicable 4. Other Approval Dates: Approval Level: Approved by General Manager July 13, 2026 (Minguo Year 115) 5. Contract Counterparty and Relationship with Company: Counterparty: XINXIN VIETNAM CONSTRUCTION COMPANY LIMITED / TAICHUANG ENGINEERING VIET NAM COMPANY LIMITED Relationship: None 6. Main Contract Contents (including total contract value, estimated investment amount, contract period, restrictions, and other important terms): Total Value: TWD 717,396,778 Contract Period: November 28, 2025 – July 13, 2026 Restrictions and Other Important Terms: None 7. Name of Professional Appraisal Firm or Company and Appraisal Result: Not applicable 8. Name of Real Estate Appraiser: Not applicable 9. License Number of Real Estate Appraiser: Not applicable 10. Specific Purpose of Acquisition: For production and operational use 11. Dissenting Director Opinions on the Transaction: None 12. Is this a Related-Party Transaction? No 13. Date of Supervisor Approval or Audit Committee Consent: Not applicable 14. Is the Appraisal Report a Limited, Specific, or Special Price? No or Not applicable 15. Has the Appraisal Report Not Yet Been Obtained? No or Not applicable 16. Reason for Not Yet Obtaining the Appraisal Report: Not applicable 17. Reasons for Significant Differences in Appraisal Results and Auditor's Opinion: Not applicable 18. Auditor Firm Name: Not applicable 19. Auditor Name: Not applicable 20. Auditor License Number: Not applicable 21. Previous Material Information Disclosure Date for the Same Event: Not applicable 22. Other Disclosures: None