Miss. Code § 25-11-124
Each employer shall pick up the member contributions required by Section 25-11-123, Mississippi Code of 1972, for all compensation earned after June 30, 1982, and the contributions so picked up shall be treated as employer contributions in determining tax treatment under the United States Internal Revenue Code and the Mississippi Income Tax Code; however, each employer shall continue to withhold federal and state income taxes based upon such contributions until the internal revenue service or the federal courts rule that, pursuant to Section 414(h) of the United States Internal Revenue Code, these contributions shall not be included as gross income of the member until such time as they are distributed or made available. The employer shall pay these member contributions from the same source of funds which is used in paying earnings to the member. The employer may pick up these contributions by a reduction in the cash salary of the member, or by an offset against a future salary increase, or by a combination of a reduction in salary and offset against a future salary increase. If member contributions are picked up they shall be treated for all purposes of the Public Employees' Retirement System in the same manner and to the same extent as member contributions made prior to the date picked up.
Miss. Code § 25-11-124