Ruth Munro's mother, Margaret McPartlin, died in September 1993 aged 73.
But a court heard she continued to draw Ms McPartlin's pensions from British Steel Corporation and Diageo.
Munro, 67, from Tullibody, Clackmannanshire, admitted defrauding the schemes of Â£18,577.
Alloa Sheriff Court was told that between 1993 and May 2015 - by which time Ms McPartlin would have been 94 - she pretended to the administrators of both pension schemes that her mother was still alive.
Sheriff Linda Smith deferred sentence for a criminal justice social work report until 10 November and ordered Munro to reappear then.
She said: "I'll continue this for reports to be made available."
It is expected that Munro's solicitor, Jay Goodwillie, will outline mitigating circumstances at the November hearing.
A woman has admitted pretending her dead mother was still alive for more than 20 years so she could carry on drawing her pension.