A woman fraudulently claimed £47,500 in tax credits after failing to tell the authorities she was living with her police officer partner.
Mother-of-three Anna Glynn, 37, received the money between October 2010 and April 2015.
The carer, from Rhyl, Denbighshire, pleaded guilty to fraud at Mold Crown Court and was given an eight-month sentence, suspended for two years. She was also ordered to carry out 240 hours' unpaid work.
During the sentencing hearing the court heard Glynn's partner knew nothing about what was happening.
"It is a great pity that you did not share your circumstances with your partner, a police officer," Judge Geraint Walters said. "Had you done so, you may have received some guidance about the inappropriateness of what was going on."
Defence barrister Simon Killeen said the relationship was "on and off" for times during the period of offending.