For those filing comprehensive income tax in May due to business income, the personal deduction logic (basic and additional deductions) works the same as year-end wage settlement. A basic deduction of KRW 1.5 million per person applies to yourself, your spouse, and dependents (annual income of KRW 1 million or less, living with you).
Freelancers and business-income earners who never go through year-end settlement can still claim personal deductions on the same basis in their comprehensive return. If you have both wage and business income, the personal deduction is applied only once against your total combined income — not duplicated.
Comprehensive tax personal deduction checkpoints
How freelancers and business owners apply for it
On the Hometax comprehensive income tax filing screen, enter each dependent's alien registration number (or passport number), relationship, and income eligibility under the personal deduction section, and the deduction is applied automatically.