Va. Code § 24.2-216
When a vacancy occurs in the membership of the General Assembly during the recess of the General Assembly or when a member-elect to the next General Assembly dies, resigns, or becomes legally incapacitated to hold office prior to its meeting, the Governor shall issue a writ of election to fill the vacancy. If the vacancy occurs during the session of the General Assembly, the Speaker of the House of Delegates or the President pro tempore of the Senate, as the case may be, shall issue the writ unless the respective house by rule or resolution shall provide otherwise. Upon receipt of written notification by a member or member-elect of his resignation as of a stated date, the Governor, Speaker, or President Pro Tempore, as the case may be, may immediately issue the writ to call the election. The writ shall be issued within 30 days of the vacancy or receipt of notification of the vacancy, whichever comes first. If the vacancy occurs or will occur between December 10 and March 1, the writ shall order the special election to be held no more than 30 days from the date of such vacancy. The member's or member-elect's resignation shall not be revocable after the date stated by him for his resignation or after the forty-fifth day before the date set for the special election.
The writ shall be directed to the secretaries of the electoral boards and the general registrars of the respective counties and cities composing the district for which the election is to be held.
Notwithstanding any provision of law to the contrary, no election to fill a vacancy shall be ordered or held if the general or special election at which it is to be called is scheduled within 75 days of the end of the term of the office to be filled.
Va. Code § 24.2-216