Leeds Crown Court heard 64-year-old Anne-Marie Turrall was full-time carer for her son Matthew, who was born in March 1984 and suffered from a number of mental and physical disabilities.
Turrall, of The Boyle, Barwick-in Elmet, Leeds, had been legitimately claiming carers allowance because she provided at least 35 hours care a week for her son.
The court heard she had also initially legitimately claimed incapacity benefit and disability living allowance on his behalf.
But she failed to notify the Department of Work and Pensions after Matthew died aged 22 in September 2006 while on a trip to visit his father in Cyprus .
Prosecutor, Ben Thomas, said the benefits continued to be paid to Turrall from September 2006 to October 2012.
Turrall’s fraud was exposed in 2012 after an investigation was launched when incapacity benefit was phased out and replaced with employment support allowance.
Mr Thomas said Turrall was overpaid a total of £85,329.61, adding: “She explained that in 2006 she had taken him to Cyprus to visit his dad and that Matthew had died on September 8 2006.
“She accepted she had not reported his death as she was struggling and later on just did not do it.” Turrall, who has no previous convictions, admitted three charges of benefit fraud.
Mitigating, Antony Sugare said: “The defendant is very remorseful. She feels a great deal of shame.”
Jailing Turrall for 14 months, Judge Simon Phillips QC, said: “I recognise that the initiation of this dishonesty was the trauma of dealing with a sick child and dealing with the grief following his death.”