It cannot be reduced. According to the provisions of Article 17 of the Measures for the Administration of Pre-tax Deduction Certificates of Enterprise Income Tax (People's Republic of China (PRC) State Taxation Administration of The People's Republic of China Announcement No.2018 No.28), except in the circumstances stipulated in Article 15 of these Measures, enterprises should obtain external vouchers such as invoices in previous years, and the corresponding expenses were not deducted before tax in that year. Obtain external vouchers such as invoices that meet the requirements in future years, or provide relevant materials that can prove the authenticity of expenditures in accordance with the provisions of Article 14 of these Measures. The corresponding expenditure can be traced back to the annual pre-tax deduction of expenditure, but the retrospective period shall not exceed five years.

Pre-tax deduction conditions that can be traced back to the year of expenditure: enterprises should obtain external vouchers such as invoices in previous years, and there is no pre-tax deduction in the corresponding expenditure year. External vouchers such as invoices are provided by other units or individuals and belong to external vouchers, while payslips are internal vouchers of enterprises and do not belong to the conditions of remuneration.

Reimbursement of wages actually occurred in enterprises. According to the enterprise income tax law or regulations, pre-tax deduction is allowed, and payment is allowed only in the year of occurrence, so it should be deducted in the year of replacement.