Konsep Nafkah Seperlunya dalam Instrumen Perlindungan Harta Bersama pada Perkawinan yang Suami Telah Memiliki Anak Biologis: The Concept of Alimony as Necessary in the Instrument of Protection of Joint Property in a Marriage Where the Husband Already Has a Biological Child - Virnanda Angelika Aguelline; Rahmida Erliyani (Jurnal Kolaboratif Sains, 2026)
Penelitian ini mengkaji kekaburan norma yang terkandung dalam frasa "nafkah seperlunya" berdasarkan Pasal 867 KUHPerdata dan implikasinya terhadap perlindungan harta bersama dalam perkawinan yang suami telah memiliki anak biologis di luar perkawinan yang sah. Latar belakang penelitian ini didasari oleh dua putusan Mahkamah Konstitusi yang saling berkaitan, yaitu Putusan MK Nomor 46/PUU-VIII/2010 yang memperluas hubungan perdata anak luar kawin hingga mencakup ayah biologisnya, serta Putusan MK Nomor 69/PUU-XIII/2015 yang memungkinkan pembuatan perjanjian perkawinan selama masa perkawinan berlangsung melalui akta notaris. Penelitian ini menggunakan metode penelitian hukum normatif dengan pendekatan perundang-undangan (statute approach) dan pendekatan konseptual (conceptual approach), bertipe doktrinal dan bersifat preskriptif. Bahan hukum primer meliputi KUHPerdata, Undang-Undang Perkawinan, Undang-Undang Jabatan Notaris, Undang-Undang Perlindungan Anak serta putusan Mahkamah Konstitusi yang relevan. Penelitian ini menyimpulkan bahwa frasa "nafkah seperlunya" dalam Pasal 867 KUHPerdata mengandung kekaburan norma yang dapat diisi melalui penerapan prinsip proporsionalitas secara kumulatif melalui tiga sub-prinsip, yaitu kesesuaian (suitability), kebutuhan (necessity), dan keseimbangan (balancing). Nafkah anak biologis wajib dipenuhi dari harta pribadi ayah biologis setelah kewajibannya kepada keluarga sah terpenuhi, dan tidak boleh membebani harta bersama tanpa persetujuan istri sah. Notaris berperan strategis secara preventif melalui pembuatan perjanjian perkawinan, penyuluhan hukum, fungsi legal filter, penciptaan kepastian hukum melalui akta otentik, serta publisitas melalui pencatatan resmi, dengan batasan bahwa Notaris tidak dapat meniadakan hak nafkah anak biologis sepenuhnya karena bertentangan dengan norma imperatif Pasal 867 KUHPerdata. ABSTRACT This study examines the normative ambiguity contained in the phrase "maintenance as necessary" under Article 867 of the Civil Code (KUHPerdata) and its implications for the protection of joint marital property in marriages where the husband already has a biological child outside of a legal marriage. The background of this research is based on two interrelated decisions of the Constitutional Court, namely Constitutional Court Decision Number 46/PUU-VIII/2010 which expands the civil relationship of children born out of wedlock to include their biological father, and Constitutional Court Decision Number 69/PUU-XIII/2015 which allows the creation of marriage agreements during the marriage period through a notary deed. This research employs a normative legal research method with a legislative approach (statute approach) and a conceptual approach, doctrinal and prescriptive in nature. Primary legal materials include the Civil Code, the Marriage Law, the Notary Law, the Child Protection Law, and relevant Constitutional Court decisions. This study concludes that the phrase "maintenance as necessary" in Article 867 of the Civil Code contains a normative vagueness that can be resolved through the cumulative application of the proportionality principle via three sub-principles: suitability, necessity, and balancing. Biological child support must be fulfilled from the biological father's personal assets after his obligations to the legal family are met, and must not burden the joint marital assets without the consent of the legal wife. Notaries play a strategic preventive role through the drafting of marriage agreements, legal counseling, serving as a legal filter, ensuring legal certainty through authentic deeds, and publicity through official registration, with the limitation that Notaries cannot completely negate the biological child's maintenance rights as this would contravene the imperative norm of Article 867 of the Civil Code.