The United States Fish and Wildlife Service (USFWS) states that non-commercial items of less than 10 kg (22 lbs), “including gifts, items not intended for sale that are carried in personal baggage or as part of a household move, and items that are personally owned and shipped to oneself” are exempt from restrictions.
Luckily, these exemptions will cover most guitars! For guitars that do not meet the requirements of the exemption, they “must be accompanied by CITES documents when traded internationally.” This restriction is only relevant if your guitar is being exported or imported across trade borders. Shipping within the United States or within the borders of the European Union should not require a CITES certification.
If you are carrying your instruments for private use (for example; On tour or simply for your own leisure), you are exempt from CITES regulations. However, if your guitar contains Brazilian rosewood, you will need formal documentation to carry it across international borders.
For more information on applications for formal documentation (an “instrument passport”) click here.