In the Iranian legal system, one of the institutions of interest in employment laws and regulations is the first month's salary, which is mainly deducted from the salaries of official government employees and paid to the Country Pension Fund. Although the first month's salary mechanism in the Iranian administrative system is more than a century old, there are numerous ambiguities and challenges regarding it; so that this issue has caused disagreements between government agencies and collective protests by some official employees who are members of the Country Pension Fund, and many of them have demanded its removal from the laws. Considering this issue, the current article, using a descriptive-analytical method and based on library studies, has examined the concept, nature, persons and payments subject to first month's salary deduction and obstacles to its deduction. This study findings indicate that there are ambiguities and disagreements regarding those subject to first month's salary deduction and payments subject to first month's salary deduction; As the Country Pension Fund, as the institution receiving the first month's allowance, wants to expand its scope, and some other government agencies have considered it limited to the cases specified in the laws. Also, completing the insurance and retirement history are considered obstacles to receiving the first month's allowance.