Couple Deduction Calculator

Couple Deduction Calculator helps estimate Korea-related employee tax credits, payroll deductions, or worker tax pressure in English.

Dual-income spouse inputs

Runs the Korean couple-deduction optimizer, which enumerates allocation combinations and keeps the Year-End Tax calculation underneath.

Spouse A

Spouse B

Maximum tax saving found

₩395,010

Optimal allocation versus the worse all-to-one-spouse case

Optimized total tax

₩7,440,372

Combined refund -₩940,372

Saving versus all to A

+₩123,750

Saving versus all to B

+₩395,010

Recommended allocation items

Child personal deduction

Spouse A

Amount tested: ₩3,000,000. Saving if assigned to A: ₩147,510; to B: ₩0.

Child tax credit

Spouse A

Amount tested: ₩550,000. Saving if assigned to A: ₩0; to B: ₩0.

Parent dependent deduction

Spouse A

Amount tested: ₩1,500,000. Saving if assigned to A: ₩0; to B: ₩0.

Family medical expense

Spouse B

Amount tested: ₩5,000,000. Saving if assigned to A: ₩0; to B: ₩266,750.

Child education expense

Spouse B

Amount tested: ₩2,000,000. Saving if assigned to A: ₩0; to B: ₩143,000.

Related calculators

Dual-income couple deduction allocation guide

This English guide translates the Korean couple-deduction optimizer. The calculator calls calculateCoupleDeduction, and that function enumerates allocation combinations while reusing calculateYearEndTax for each spouse.

What can and cannot be allocated

The Korean article starts with the key point: not every deduction can be freely moved between spouses. Personal deductions for children or parents, child tax credits, family medical expenses, child education expenses, and some donation items may depend on which spouse claims the dependent.

Other deductions generally stay with the person who paid or owns the account. Credit card spending stays with the cardholder, pension savings and IRP credits stay with the account holder, insurance premium credits follow the policyholder, and personal medical or education expenses are generally claimed by the person concerned.

Why marginal rate and the 3% medical threshold matter

A personal deduction of KRW 1,500,000 is more valuable when assigned to the spouse in the higher marginal tax-rate bracket. At a 24% marginal rate it can reduce tax by about KRW 360,000 before local tax effects, while at a 15% marginal rate the benefit is smaller.

Medical expenses are different because the deductible base is only the amount above 3% of gross salary. The Korean content explains that assigning family medical expenses to the lower-salary spouse can clear the 3% medical-expense threshold more easily, but the result must still be compared with the personal-deduction and tax-credit capacity of each spouse.

Optimization logic

The optimizer compares all active allocation combinations, including child deductions, parent deductions, family medical expenses, and child education expenses. It calculates both spouses through the same year-end-tax engine, then selects the combination with the lowest combined final tax.

The result also compares the optimized case against all-to-spouse-A and all-to-spouse-B scenarios. This mirrors the Korean page because the practical question is not only who should claim an item, but how much additional refund or tax saving the optimized allocation creates.

Annual review cautions

The Korean article warns that the best allocation can change every year. Salary changes, promotion, childbirth, parents becoming dependents, medical spending, education spending, rent, pension contributions, and donation records can move a couple into a different bracket or change unused tax-credit capacity.

Duplicate dependent claims should be avoided. If both spouses claim the same dependent or related deduction, the tax office can deny one claim and impose additional tax or penalties. Couples should agree on the allocation before filing with each employer or through Hometax.