OAKLAND (CBS/AP) — An audit shows Oakland is keeping cash from overpaid parking tickets despite a state law requiring refunds.

Motorists mistakenly paid parking tickets twice, adding to a $316,000 windfall last year alone.

The city auditor said Oakland’s parking enforcement officers issued $22.7 million in tickets last year.

The $316,000 in overpayments came from inattentive motorists who paid twice.

The annual windfall was discovered as part of a larger audit of the city’s parking ticket management.

The auditor said Oakland bureaucrats have no knowledge of the requirement to reimburse overpayments.

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