Group 1 - The article discusses the conditions under which expenses can be deducted for tax purposes when invoices cannot be reissued due to special circumstances such as business license cancellation or being classified as an abnormal taxpayer [4] - It specifies that necessary documentation for proving the authenticity of expenses includes proof of the inability to reissue invoices, contracts or agreements related to business activities, non-cash payment vouchers, transportation proof, internal inventory records, and accounting records [4] - The article clarifies that when calculating the deduction limits for business entertainment expenses, advertising expenses, and promotional expenses, the sales revenue should include deemed sales revenue [4][6] Group 2 - It outlines the requirements for deducting union dues from corporate income tax, stating that dues not exceeding 2% of total salary can be deducted with a receipt issued by the union [6] - The article references several tax regulations and announcements that provide the legal framework for the discussed tax treatments, including guidelines on corporate income tax deductions and the handling of union dues [6]