Core Viewpoint - The article discusses the handling of abnormal tax deduction certificates, outlining the criteria for categorizing invoices as abnormal and the corresponding processing methods for taxpayers [2][10]. Abnormal Certificate Criteria - Six scenarios classify invoices as abnormal tax deduction certificates: 1. Loss or theft of tax control equipment with unissued or unuploaded invoices [2]. 2. Non-compliant taxpayers failing to report or pay taxes [3]. 3. Invoices flagged by the tax management system for discrepancies [4]. 4. Invoices identified by big data analysis as potentially fraudulent or non-compliant [5]. 5. Invoices from businesses that have gone missing during their operational period, with specific conditions regarding the nature of goods and production capabilities [5][6]. 6. Invoices where the input tax exceeds 70% of total input tax or exceeds 50,000 yuan [7][8]. Processing Methods for Abnormal Certificates - Five processing scenarios for abnormal tax deduction certificates: 1. For invoices not yet declared for input tax deduction, no deduction is allowed [11]. 2. For invoices already declared, input tax must be reversed unless otherwise specified [12]. 3. For export tax refunds, if not declared or processed, refunds are not allowed [13]. 4. A-grade taxpayers can apply for verification within 10 working days if they have received abnormal certificates [16]. 5. Taxpayers can contest the classification of invoices and request verification from tax authorities [18]. Verification of Invoices - Taxpayers can verify the information of VAT invoices through the National Taxation Administration's verification platform [19]. Policy References - The article cites several policy documents that govern the management of abnormal VAT deduction certificates [21].