When the governing board of any county, city, town or school district shall determine by proper resolution in writing that a surplus exists in any building fund created under the provisions of Section 10, Article X, Oklahoma Constitution, not required for the completion of the purpose for which said taxes were levied and collected, or where said proposed construction has been abandoned, said surplus shall be refunded to the taxpayers by the use thereof by the county excise board to reduce the tax levy for the sinking fund of the municipality for which the building fund was created. Provided, that any portion of said building fund surplus not required to eliminate a sinking fund tax levy for said municipality shall be refunded to the taxpayers by the use thereof to reduce the tax levy for the benefit of the general fund for the same municipality.