Reece Gibson (22) took the key from the “secure place” his father had been keeping it and then let himself into the woman’s home to steal the cash.
When she returned home after a few days she discovered the money missing and there was no sign of forced entry so her suspicion fell on her ex-partner.
When it was revealed Gibson was the culprit police were called and he admitted the offence.
He claimed he took the cash to the woods to hide it and when he returned later to collect it, the wad of notes was no longer there.
Gibson appeared at Falkirk Sheriff Court last Thursday having pleaded guilty to the break-in and theft he committed at an address in Hadrian Way, Bo’ness, between February 24 and February 27.
Michael Maguire, procurator fiscal depute, said: “The complainer is the ex-stepmother of the accused. She had left her house for a few days and left her key with her ex-partner, who is the accused’s father.
“When she returned home she let herself in. There had been no sign of damage to doors or windows and when she went into her bedroom to check her cash she noticed £400 was missing.
“She asked her partner if he knew anything about it and he said he didn’t take it, adding he kept her key in a secure place in his house. The accused admitted he took the £400 and said he hid it in the woods to keep it safe and when he went back later to get the money it wasn’t there.
“There was no recovery of the money.”
Defence solicitor Gordon Addison said the woman had been reimbursed.
He added: “His father has paid the money back to his ex-partner on his son’s behalf and now he owes his father the money.”
Sheriff Derek Livingston noted Gibson was a first offender but said the offence was a serious breach of trust.
Gibson, 1 Drumpark Avenue, Bo’ness, was placed on a community payback order with the condition he complete 80 hours of unpaid work within four months.