Each commissioner other than the chair is entitled to an annual salary of $5,600. The chair of the Commission is entitled to an annual salary of $6,100. All salaries shall be paid monthly from the administrative tax collected by the Commission under § 18–307 of this article. Subject to subparagraph (ii) of this paragraph, each commissioner is entitled to an annual expense allowance not exceeding $2,400, in accordance with rules and regulations the Commission adopts. A commissioner shall submit a voucher showing the expenses. With the approval of the County Executive of Montgomery County, the County Council may authorize an appropriate supplementary salary for the commissioner designated by Montgomery County to serve on a full–time basis. If the County Executive fails to approve a supplementary salary authorization by the County Council within 30 days after the authorization is submitted, the County Council, by an affirmative vote of eight of its members, may authorize the supplementary salary without the approval of the County Executive. On the recommendation of the County Executive of Prince George’s County, the County Council may authorize an appropriate supplementary salary for the commissioner designated by Prince George’s County to serve on a full–time basis. Any supplementary salary authorized under this subsection shall be paid from the administrative tax collected by the Commission under § 18–307 of this article.