"I didn't think I'd hear any more about my grandfather, whom I never knew," Martine Courtois told AFP, after reading the €13 ($18) land inheritance tax bill addressed to her grandfather, Pierre Barotte.
"Everything was done legally at the time, we didn't get any demands from the tax office," said Courtois, who lives in the small eastern town of Bruyeres.
The local tax office said the situation was entirely normal and "happens all the time" when an unpaid tax debt, through interest or late payment fees, goes beyond €12.
"The day the money due goes over this threshold, the machine gets going," a tax spokesman told AFP, asking not to be named.
The family "probably didn't settle everything up for the inheritance," he said, pending an investigation of Barotte's case.
Courtois has not paid the bill and instead sent a letter to the tax office: "My grandfather died in 1949, please do what's necessary."