Group 1 - The article discusses the procedures for enterprises to handle costs and expenses that lack valid documentation for tax deductions, emphasizing the importance of obtaining proper invoices or external vouchers for tax compliance [3][4][8] - It outlines that if an enterprise fails to obtain necessary invoices or vouchers, they can provisionally account for these costs based on recorded amounts during quarterly tax prepayments, but must provide valid documentation during annual tax reconciliation [3][4] - The article specifies that enterprises can still claim tax deductions for expenses incurred in previous years if they obtain valid invoices or documentation within five years of the expense occurrence [8] Group 2 - It highlights the necessary documentation required for tax deductions, including contracts, payment vouchers, and internal records, with specific emphasis on the need for valid invoices or vouchers to substantiate claims [6][8] - The article mentions that if an enterprise cannot obtain invoices due to reasons such as the counterparty's business license cancellation, they can still provide alternative proof of expenditure for tax deduction eligibility [4][6] - It also addresses the treatment of employee compensation, indicating that wages accrued in one year but paid in the following year can be deducted during tax reconciliation [10][20]