She was employed as a secretary and was entrusted by the school's principal to tend to the school bank accounts and update school accounting software.
The school's credit card was also entrusted to her care and she signed it out to staff members as they required it for their jobs.
In 2009 the period of offending began and continued for six years until it stopped in February this year .
During this time she made about 30 un-approved transactions totalling about $150,000 from the school's bank accounts to accounts belonging to her and her husband.
She also racked up $6843.16 on the school's credit card.
While McCartney has admitted these facts, the police prosecutor said there was some dispute about the two figures as the defendant claimed she did not steal that much money.
The school became aware of this offending in late April, after which the principal and board of trustees met the then-employee.
She admitted her offending during the meeting and her employment was terminated.
The maximum penalty for both of these offences is seven years' imprisonment.
McCartney will return to court for sentencing next month.
The latest Education Review Office report in September last year stated the roll at the school was 563.
