우리나라 헌법 제11조 제1항은 “모든 국민은 법 앞에 평등하다”는 일반적 평등원칙을 보장하고 있다. 이러한 헌법상 평등권에 대한 위헌심사기준은 자의금지원칙과 비례의 원칙을 적용하고 있다. 조세평등주의는 헌법에 규정된 평등권 조항을 조세법에서 구현하여 조세정의를 실현하려는 원칙이다. 본 연구는 평등권에 대한 심사기준과 조세평등주의에 대하여 살펴보고, 국외근로자비과세범위에 대한 차별취급의 정당성과 그것이 헌법상 평등원칙에 위반되는 것은 아닌지 분석하였다. 국외근로자는 국외의 육상에 근무하는 일반근로자와 해상의 원양・외항선근로자, 공중의 항공근로자를 포함하고 있다. 국외근로자비과세범위는 소득세법 제12조(비과세소득)에 근거를 두고 있다. 대통령령으로 정한 소득세법시행령 제16조 제1항 1호(국외근로자의 비과세급여의 범위)에서 그 범위를 정하며, 1976년 규정신설 시부터 2006년까지 30년간 동일한 취급을 해왔다. 그러나 법 개정 후 현재 일반국외근로자와 국제선항공근로자의 비과세범위는 월100만원인 반면 해외건설근로자와 원양・외항선근로자는 월300만원으로 3배에 이르는 차별취급이 발생하고 있다. 차별의 이유는 해외취업이 고소득 전문직 중심으로 전환된 점과 해외오지건설의 열악한 근무환경, 건설근로자의 국외진출지원 등이었다. 본 연구의 주요 결과로 이러한 차별취급은 본질적으로 같은 것을 다르게 차별취급하면 안 된다는 평등권의 자의금지원칙 위반소지가 있는 것으로 나타났다. 비례의 원칙에 있어서 차별취급의 적합성은 시행령개정의 절차와 건설근로자의 국외진출지원 등 입법목적의 정당성은 인정될 수 있는 부분은 있다. 그러나 반드시 차별취급을 해야만 입법목적을 달성하는 것은 아니었기 때문에 차별취급의 필요성은 부족해 보이고, 각 직종의 근무환경과 임금, 인력수급문제 등을 비교해 볼 때 해외건설근로자와 원양・외항선근로자만 비과세범위를 3배로 차별취급 하는 것은 법익의 균형성에 문제가 발생할 여지가 있어 비례의 원칙 위반소지도 있어 보인다. 따라서 소득세법시행령 제16조 제1항 1호의 개정은 차별취급을 정당화하는 합리적인 이유를 찾기 어렵고, 헌법상 평등권의 자의금지원칙과 비례원칙에 반하여 조세평등의 원칙에서 자유롭지 못한 것으로 보인다. 이러한 차별취급문제를 개선하여 조세평등주의에 대한 위헌성문제를 해결하고 우리 헌법의 기본정신인 평등원칙을 구현할 필요성이 있다고 보여 진다.
Article 11(1) of the Constitution of the Republic of Korea, ‘All citizens shall be equal before the law,’ guarantees the general principle of equality. The criteria for the scrutiny of unconstitutionality in regard to the constitutional right to equality apply the principle of arbitrariness prohibition and the principle of proportionality. The principle of equality in taxation is a principle to realize tax justice by embodying the constitutional provision of the right to equality in the tax act. This study looked into the criteria for the scrutiny of unconstitutionality in regard to the right to equality and the principle of equality in taxation, examined whether discriminatory treatment in the scope of non-taxable wages for workers abroad is justifiable, and analyzed whether the discriminatory treatment violates the constitutional principle of equality. The workers abroad include general workers working on overseas land, maritime workers on a pelagic fishing vessel or a vessel serving an overseas route, and workers providing labor in an aircraft serving an overseas route. The scope of non-taxable wages for workers abroad is based on Article 12 (Non-Taxable Income) of the Income Tax. The scope is prescribed by Article 16 (1) 1 (Scope of Non-Taxable Wages for Workers Abroad) of the Enforcement Decree of the Income Tax, which is a Presidential decree, and has been applied in the same way for a period of 30 years from 1976 when the provision was newly established to 2006. At present, however, there is discriminatory treatment in the scope of non-taxable wages, considering that of KRW 3 million per month for overseas construction workers and workers on pelagic fishing vessels or vessels serving overseas routes, which is three times as large as that of KRW 1 million per month for general workers abroad and workers on aircraft serving overseas routes. The reasons for the revision of the act were the switch of overseas employment to high income professions, the poor working environment of overseas remote-area construction, and support to construction workers’ overseas employment. As a result of the examination of this study, it was found that such discriminatory treatment could be in violation of the principle of arbitrariness prohibition for the right to equality, to the effect that the essentially same things should not be treated with discrimination. As for the appropriateness of discriminatory treatment, although there is some justifiability of the legislation purpose to be achieved through the discriminatory treatment, such as the procedure for the revision of the enforcement decree and support to construction workers’ overseas employment, the necessity for discriminatory treatment seems not very great because the legislation purpose is not necessarily achieved only through the discriminatory treatment. In addition, to compare working environment, wages, and manpower supply &demand among occupational categories, the discriminatory treatment in the scope of non-taxable wages for overseas construction workers and workers on pelagic fishing vessels or vessels serving overseas routes, which is three times as large as that of the others, might create a problem in terms of the balance of legal interests Thus, it seems that the discriminatory treatment could be in violation of the principle of proportionality, a criterion for the scrutiny of unconstitutionality in regard to the right to equality. Therefore, it is judged that it is difficult to find any reasonable reason for justifying the discriminatory treatment in the revision of Article 16(1)1 of the Enforcement Decree of Income Act, and that the revision is opposed to the principle of arbitrariness prohibition and the principle of proportionality for the constitutional right to equality, and is subject to the restriction of the principle of equality in taxation. It is believed that it is necessary to improve such a problem of discriminatory treatment, thereby solving the problem of non-constitutionality in connection with the principle of equality in taxation and implementing the principle of equality, the basic spirit of our constitution.