In a spa setting, it is customary to give a massage therapist a 15-percent to 20-percent tip, according to About.com. In a medical or clinical setting, tips are usually discouraged. In both cases, giving the therapist client referrals is another way to show appreciation for services received.
If a spa is located in a hotel or resort, an 18 percent to 20 percent service fee, or "spa tip," may be added to the cost of the massage automatically. A good massage therapist discloses these fees beforehand, and if such fees are present, there's no obligation to offer a tip unless service was exceptional. Day spas don't usually include automatic gratuities.
If a massage was purchased at a discount because of a promotion, the therapist's tip should be based on the regular cost of the massage rather than the discounted rate. The therapist spends the same amount of time with a client regardless of the promotions and should be tipped accordingly.
Medical spas tend to discourage tipping, since therapists in medical spas use body work to treat specific health conditions, and tips are generally not accepted in the healthcare industry. A doctor or nurse doesn't expect a tip for his services, and neither do the massage therapists working in medical settings.