The Federal credit unions organized hereunder, their property, their franchises, capital, reserves, surpluses, and other funds, and their income shall be exempt from all taxation now or hereafter imposed by the United States or by any State, Territorial, or local taxing authority; except that any real property and any tangible personal property of such Federal credit unions shall be subject to Federal, State, Territorial, and local taxation to the same extent as other similar property is taxed. Nothing herein contained shall prevent holdings in any Federal credit union organized hereunder from being included in the valuation of the personal property of the owners or holders thereof in assessing taxes imposed by authority of the State or political subdivision thereof in which the Federal credit union is located; but the duty or burden of collecting or enforcing the payment of such a tax shall not be imposed upon any such Federal credit union and the tax shall not exceed the rate of taxes imposed upon holdings in domestic credit unions.