Is an HUF deed mandatory under Hindu law?
No — an HUF comes into existence by law upon birth in a Hindu family (or under the Hindu Adoptions and Maintenance Act for Sikh/Jain families). However, a written deed is essential to formally document the karta, enumerate coparceners, and establish which assets belong to the HUF versus individual members. Without a deed, the HUF exists in law but has no documentary basis for PAN, ITR, or bank account.