As treasurer, O'Leary has introduced numerous innovations to the treasury operations of Arlington County, including the Pay at the Bank program in 1984, which allows Arlington tax payers to pay taxes at local bank branches; the Pay by Credit Card program, initiated in 1985, which made Arlington the fourth jurisdiction in Virginia to accept credit card payments for taxes; the Automated Payment System begun in 1987, which allows taxes to be automatically debited from a bank account or charged to a credit card; and the Tax Assist Program (later renamed the Taxpayer Assistance Program), begun in 1994, which makes secured loans to taxpayers in need of assistance to pay their taxes on time.