Upon the written request of the district commission made concurrently to both boards of supervisors pursuant to subdivision 8 of § 15.2-4606, each board of supervisors may levy and collect an annual special improvements tax on taxable real estate zoned for commercial or industrial use or used for such purposes and taxable leasehold interests in that portion of the improvement district within its jurisdiction. Notwithstanding the provisions of Article 4 (§ 58.1-3229 et seq.) of Chapter 32 of Title 58.1, the tax shall be levied upon the assessed fair market value of the taxable real property. The rate of the special improvements tax shall not be more than $0.20 per $100 of the assessed fair market value of any taxable real estate or the assessable value of taxable leasehold property as specified by § 58.1-3203. Such special improvement taxes shall be collected at the same time and in the same manner as county taxes are collected, and the proceeds shall be kept in a separate account. The effective date of the initial assessment shall be January 1 of the year following adoption of the resolution creating and establishing the district. All revenues received by each county pursuant to such taxes shall be paid to or at the direction of the district commission for its use pursuant to §§ 15.2-4606 and 15.2-4608.