Cancellation of building permits.

In any case where building permits have been issued and no work has been begun thereunder, the person who has paid the fee for said permit may return said permit for cancellation, and upon the cancellation thereof there shall be refunded to him, in the manner prescribed by law for the refunding of erroneously paid taxes, the amount of said fee less the actual expense incident to the issuance of said permit, as determined by the Inspector of Buildings; provided, that application for such refund shall be made within 6 months after the issuance of said permit.