The actor and reality TV star was held in contempt of court on 9 March (17) after his former spouse Mary Jo Eustace filed a complaint in October (16), accusing him of missing multiple payments to support their 18-year-old son Jack.
MCDermott told the Los Angeles judge he had "fallen on hard times", and was about to be handcuffed when the official decided to give him one last chance to make amends with Eustace by giving them the opportunity to work out a deal.
His ex subsequently withdrew her complaint, sparing MCDermott jail.
As part of the agreement, he had until Monday (13Mar17) to hand over half of the outstanding amount, and MCDermott made good on his promise as he handed over $2,500 (£2,000) in cash to meet the deadline.
His next payment is due on 1 April (17), according to the New York Post's gossip column Page Six.
If MCDermott fails to honour the deal, Eustace will refile her complaint, which could land Spelling's man behind bars.
MCDermott wed Eustace in 1993, but left her after falling in love with Spelling when the pair filmed TV movie Mind Over Murder together in 2005.
The actors went on to marry in 2006 and are parents to five children: Liam, nine; Stella, eight; Hattie, five; Finn, four, and Beau, who was born earlier this month (Mar17).
MCDermott wasn't lying when he claimed he was struggling financially - he and Tori are also facing legal action over an unpaid bank loan, while the actress daughter of late TV producer and multi-millionaire Aaron Spelling was recently ordered to settle an outstanding credit card debt.