The obligation, and where it comes from
Several provisions operate together: the maintenance provisions of the Bharatiya Nagarik Suraksha Sanhita which apply across communities, the Hindu Adoptions and Maintenance Act, and the interim maintenance powers of the court hearing the matrimonial matter. A claim can usually be brought under more than one, and the choice affects speed.
The obligation continues for a minor child irrespective of who has custody, and for a daughter it has been held to continue until she is married in appropriate cases. For a child with a disability, the obligation can extend into adulthood.
How the amount is arrived at
Courts do not use a fixed formula, but the factors are consistent and the calculation is more predictable than parents expect.
Enforcing an order that is not being paid
Non-payment is common and the remedies are real. Arrears can be recovered by execution, the court can direct attachment of salary through the employer, and persistent default can result in a warrant and detention.
We usually recommend keeping a clean record of every demand and every payment received, and applying promptly rather than allowing arrears to build over years. Courts respond better to an application made after three months of default than after three years of silence.