Optimizing family taxation and its limits

Indonesia treats the family as a single economic unit for income tax under Article 8(1) of the Income Tax Law. With the Coretax administration system operational, this family tax unit is operationalised through the Family Unit Data (DUK) under PER-7/PJ/2025, while Government Regulation 20/2026 extends family-income aggregation into the final-tax regime for micro, small, and medium enterprises (MSMEs). Using a juridical-normative and policy-analysis approach supplemented by illustrative tax-burden simulations with sensitivity analysis, this study critically examines how PP 20/2026 operationalises family aggregation in the MSME regime and analyses its gendered implications. Three findings emerge. First, aggregating spouses' gross turnover under Article 58 can push a couple past the Rp4.8 billion threshold and strip the 0.5% final rate, so a household's tax burden can surge between 3.3 and 25.5 times (baseline 10.5 times) between years depending on net margins, while the same threshold is applied per individual for bookkeeping and the Rp500 million exemption, producing internal inconsistency. Second, because women manage most Indonesian MSMEs, this aggregation burdens women disproportionately: a wife's final-rate eligibility now depends on her husband's turnover, which she has no right to access, creating an information asymmetry that weakens self-assessment and, measured against optimal-tax theory, taxes the second earner precisely as the primary earner's income rises. Third, the DUK architecture centres the family on the husband, subordinating the wife as an equal tax subject. The study recommends replacing the distortive proportional mechanism with a binary choice and redesigning the DUK so that spouses are equal, independent subjects.