Perbedaan penetapan awal bulan Kamariah selalu mengundang polemik yang karena perbedaan metode, aliran serta adanya perbedaan mathla’. Indonesia menggunakan konsepsi mathla’ wilayah Indonesia namun, realitanya saat ini masih terjadi distorsi terkait batasan secara geografis pada wilayah Indonesia dalam perhitungan awal bulan Kamariah. Sebagaimana yang tercantum dalam Undang-Undang Republik Indonesia No. 43 tahun 2008 Tentang Wilayah Negara bahwa wilayah NKRI meliputi darat, laut, dan udara. Maka demikian, timbul pertanyaan bagaimana ideal batas Mathla’ geografis wilayah Indonesia pada Kriteria Neo Visibilitas MABIMS? Dan bagaimana hukum penerapan batas Mathla’ geografis wilayah Indonesia pada Kriteria Neo Visibilitas MABIMS?
Penelitian ini merupakan penelitian library research bersifat kualitatif yang dianalisis secara deskriptif kualitatif kemudian proses penyimpulan deduktif dan induktif. Pengumpulan data dilakukan dengan metode dokumentasi berupa Ad-Referendum Persetujuan Kriteria Imkanur Rukyah Baharu MABIMS, kemudian ditambah dengan wawancara bersama pakar ilmu falak dan astronomi serta pemerintah (Kemenag RI). Data-data yang diperoleh dianalisis dengan pendekatan hukum Islam berlandaskan Syar’i dengan metode ijtihad istishlahi dan hukum positif melalui pendekatan yuridis-normatif dengan menelaah peraturan perundang-undangan yang selanjutnya dipertajam dengan pendekatan konseptual (Conseptual Approach).
Hasil penelitian ini menunjukkan bahwa batas ideal jangkauan mathla’ geografis wilayah Indonesia pada kriteria Neo Visibilitas MABIMS berdasarkan hukum positif, astronomi dan fikih adalah wilayah daratan dan perairan yang memiliki kedaulatan penuh serta zona-zona maritim yang berada dalam yurisdiksi nasional Indonesia yaitu Laut Teritorial, Perairan Kepulauan dan Perairan Pedalaman dimana memiliki kekuatan hukum yang sama baik di darat dan di laut. Secara Syar’i hilal yang terlihat di wilayah laut sah secara hukum Islam dan sudah seharusnya melakukan titik hisab perhitungan awal bulan tidak di darat saja tetapi di wilayah laut yang masih dalam zona kedaulatan wilayah geografis Indonesia.

ABSTRACT:
Differences in determining the beginning of the lunar month always invite polemics due to differences in methods, schools, and differences in mathla'. Indonesia uses the concept of mathla' Indonesian territory however, in reality there are still distortions regarding the geographical boundaries of Indonesian territory in the initial calculation of the lunar month. As stated in the Law of the Republic of Indonesia No. 43 of 2008 concerning State Territories that the territory of the Republic of Indonesia includes land, sea, and air. Thus, what is the ideal Mathla' geographical boundary for the Indonesian territory in the MABIMS Neo Visibility Criteria? And what is the law on applying Mathla's geographical boundaries in Indonesia to the MABIMS Neo Visibility Criteria?
This research is a qualitative research library research which is analyzed descriptively qualitatively then the process of deductive and inductive conclusions. Data collection was carried out using the documentation method in the form of an Ad-Referendum for the Approval of Imkanur Rukyah Baharu MABIMS Criteria, then coupled with interviews with experts in Islamic astronomy and astronomy as well as the government (Kemenag RI). The data obtained were analyzed using an Islamic legal approach based on Syar'i with the ijtihad istishlahi method and positive law through a juridical-normative approach by examining statutory regulations which were further sharpened by a conceptual approach (Conceptual Approach).
The results of this study indicate that the ideal boundaries of the geographical reach of the Indonesian territory on the MABIMS Neo Visibility criteria based on positive law, astronomy, and jurisprudence are land and water areas that have full sovereignty as well as maritime zones that are within Indonesia's national jurisdiction, namely the Territorial Sea, Waters Islands and Inland Waters which have the same legal force both on land and at sea. According to Syar'i, the new moon seen in the sea area is legal according to Islamic law and it is supposed to do the reckoning at the beginning of the month not only on land but in the sea area which is still in the zone of sovereignty of Indonesia's geographical area.