Short answer: No. For doing Atthai Tap, Jain scriptures require taking a proper pachchakkhān/pratijñā (vow) and observing the conduct of fasting with care and purity. “Chhod” and “Chandarvo” are local/community customs for permission and public blessings; they are not scriptural requirements.

Essential (scriptural) points

• Take pachchakkhān:

- Shwetāmbara: Take pachchakkhān from an Ācārya/Muni/Sādhvī. If unavailable, from a learned upādhyāy or a shrāvaka in samayik, invoking Dev-Śāstra-Guru and reciting Navkār. - Digambara: Take the vow (pratijñā) before Ācārya/Muni/Āryikā; if unavailable, before a qualified shrāvaka with desāvakāśika-type restraint and śuddha-bhāva.

• Keep the fast with samiti, guptis, daily pratikraman/pratyākhyān, svādhyāy, and maitri-bhāva.
• Break the fast (parṇā) correctly, with due maryādā.

About “Chhod” and “Chandarvo”

• Chhod: family/sangh permission-blessing—good for safety and harmony, especially for minors—but optional.
• Chandarvo: a community custom (announcement/blessing/cloth) in some regions—also optional.
• If your local sangh follows these customs, you may observe them for maryādā, but they are not mandated by the āgamas.

Health and suitability

• Only undertake Atthai if health permits; otherwise do a lighter vratas (e.g., upavās with jala, ekāsana/ayambil, or alpa-tap) with the right bhāva.
• Minors should always take parental consent and guidance from a guru.

May your tapas be steady, with ahimsā, vinaya, and śuddha-bhāva.