Rajeev Sabharwal (43) and his wife Renu (38) gave poison to their son Tushar (6) before consuming it themselves this morning.
Rajeev was unemployed for the last two years and under depression for not being able to pay various debts, police said.
"His (Rajeev) relatives were offering him financial help, but it was not sufficient to run the family," a police official said.
A suicide note, recovered from the spot, read that no one should be held accountable for the extreme step.