Va. Code § 15.2-2323
The amount of impact fees to be imposed on a specific development or subdivision shall be determined before or at the time the site plan or subdivision is approved. The ordinance shall specify that the fee is to be collected at the time of the issuance of a building permit. The ordinance shall provide that fees (i) may be paid in lump sum or (ii) be paid on installment at a reasonable rate of interest for a fixed number of years. The locality by ordinance may provide for negotiated agreements with the owner of the property as to the time and method of paying the impact fees.
The maximum impact fee to be imposed shall be determined (i) by dividing projected road improvement costs in the impact fee service area when fully developed by the number of projected service units when fully developed, or (ii) for a reasonable period of time, but not less than ten years, by dividing the projected costs necessitated by development in the next ten years by the service units projected to be created in the next ten years.
The ordinance shall provide for appeals from administrative determinations, regarding the impact fees to be imposed, to the governing body or such other body as designated in the ordinance. The ordinance may provide for the resolution of disputes over an impact fee by arbitration or otherwise.
Va. Code § 15.2-2323