Belinda Yaxley, 44, who was chair of the Norfolk Federation of Parent Teacher Associations when it stopped meeting in 1998, pleaded guilty to the charges at Norwich Crown Court last Monday.
Yaxley, of Hainford, had asked Karen Sillet, a former committee member, to countersign three cheques in August 2001, claiming they were for expenses incurred by the Norfolk federation.
However, Yaxley used the cheques to withdraw pound;3,162.47 from the federation's bank account, allegedly to pay off personal debts.
When the Norfolk organisation stopped meeting, Yaxley, who was charged on July 17 last year, was the only remaining member of the group.
She will return for sentencing on April 14.
On October 14 last year, Yaxley pleaded not guilty to four counts of theft, and in January this year the prosecution changed the charges to three counts of obtaining funds through deception.
In the mid 1990s Yaxley was the membership secretary of the NCPTA. In 1997, Sandi Marshall and Sean Rogers, two former trustees, called on Yaxley to quit her pound;10,000-a-year post and pay back thousands of pounds in salary and expenses.
The Charity Commission investigated the claim that Yaxley was not entitled to her job because she had applied for the position while she was a trustee of the NCPTA.
The commission later agreed that she could keep her job.
Yaxley resigned before October 1998 when the NCPTA was restructured as a result of the Charity Commission inquiry.