(a) Each member of the Legislature who does not commute daily shall receive the sum of $131 per day as per diem allowance in connection with any regular, extended, extraordinary session, interim assignment or for any member authorized by the presiding officer. Any member of the Legislature who does commute daily shall receive the sum of $55 per day as the per diem allowance and, in addition to the allowance, shall be reimbursed for overnight commuting expenses at the mileage rate equal to the amount paid by the travel management office of the Department of Administration for the most direct usually traveled route, if travel is by private automobile, or for actual transportation costs for direct route travel, if travel is by public carrier, or for any combination of the means of transportation actually used, plus the costs of necessary taxi or limousine service, tolls and parking fees in connection with the travel: Provided, That the total of this per diem allowance plus travel expense for a daily commuting member may not exceed $131 per day. The amount for mileage paid pursuant to this subsection may change from time to time in accordance with changes in the level of reimbursement by the travel management office.

(b) The President of the Senate and the Speaker of the House of Delegates, the chairman of the house committee on finance, the chairman of the Senate committee on finance, the chairman of the house committee on the judiciary, the chairman of the Senate committee on the judiciary, and up to six additional persons from each house designated by the presiding officer pursuant to section four of this article, shall be reimbursed for travel at the rate established in subsection (a) of this section, and shall further receive the per diem allowance established in the subsection in connection with business which is related to their duties as officers at the times when the Legislature is not in regular, extended or extraordinary session, and interim committees are not meeting.