Kindly find the replies to your inquiries:

(1) When a foreign worker applies the flat tax rate (19%) for the year-end settlement, the employer's share of social security insurance premiums is included in the taxable base. (Health insurance premiums, employment insurance premiums, and long-term care insurance premiums are included, while national pension insurance premiums are not included.) Generally, the employer's share of social security insurance premiums for residents is considered non-taxable income according to Article 12 of the Income Tax Act. However, when applying the tax exemption for foreign workers under Article 18-2 of the Special Tax Treatment Restriction Act, the provisions related to non-taxable income are not applicable, so it is included in the taxable base. (Article 18-2 of the Special Tax Treatment Restriction Act)

(2) If social insurance premiums are paid through notifications, it is considered as belonging to the business year in which the notification date falls. If paid voluntarily, it should be regarded as belonging to the business year in which the payment date falls. (Corporation, SeoI 46012-11116, May 29, 2002)
 
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