Group 1 - The article discusses the types of tax deduction vouchers, categorizing them into internal and external vouchers, with specific definitions for each type [4][5]. - Internal vouchers are self-made documents used for accounting original evidence of costs, expenses, and other expenditures, which must comply with national accounting laws and regulations [5]. - External vouchers are obtained from other entities or individuals to prove the occurrence of expenditures, including invoices (both paper and electronic), tax payment certificates, and receipts [5]. Group 2 - Companies must obtain tax deduction vouchers for expenditures to calculate taxable income for corporate income tax [6]. - There is a time requirement for companies to acquire these vouchers before the end of the annual corporate income tax settlement period [7]. - If a company fails to obtain the necessary invoices or vouchers, it can request replacements before the settlement period ends, provided the expenditures are real and have occurred [8]. Group 3 - After the settlement period, if tax authorities identify missing or non-compliant vouchers, companies must replace them within 60 days of notification [10]. - Companies can also claim deductions for expenditures from previous years if they obtain compliant vouchers or provide evidence of the expenditure's authenticity within five years [11]. Group 4 - Companies are advised to retain all materials related to tax deduction vouchers, including contracts, expenditure evidence, and payment vouchers, to verify the authenticity of the vouchers [14]. - If companies fail to replace non-compliant vouchers or provide the necessary evidence, the corresponding expenditures cannot be deducted in the year they occurred [14].