You must be 18 to sign the HeadCount volunteer waiver. Volunteers below 18 are considered on a case-by-case basis, and must have their parent or guardian complete a permission form. All of this is part of the HeadCount volunteer sign-up process. If you are below the age of 21, there may be some shows you can not volunteer at because the venue or concert is limited to those 21 or over. However, this is not very common.