Selfless service in Indian tradition equates with the notion of Karma Yoga. The idea pertinent to it is to perform service for a noble cause someone believes in. This service is not rewarded by remuneration or other kinds of material gain but by accumulation of merits, an account said to be kept by deities in heaven.
The concept of selfless service is well known in all spiritual tradition of the world. No spiritual tradition fails to emphasize on the importance of offering work to people or spiritual organizations for the advancement of the noble causes they promote. Kaula Tantra as ancestral spiritual concept encourages people to spend time in selfless service. There are however specific issues in the case of Kaula Tantra spiritual path. This is mainly because of the particular kind of relationship between a Kaula Tantra guru and a disciple.
Kaula Tantra Gurukul, that is the time a disciple is dependent on a guru, is very transitory lasting for the time of initiation (Kaula Diksha) only. Certainly it can be said that there are no obligations between people involved in Kaula Tantra. However this issue does not invalidate the need of a disciple to accumulate merits both on earthly and heavenly planes.
The selfless service in Kaula Tantra has to be seen more as a voluntary action rather than an obligation like the Yogic Gurukul has. It is in the interest of a Kaula Tantra aspirant towards obtaining full Kaula Tantra initiation (Purna Kaula Tantra Diksha) to perform selfless service for a known Kaula Tantra guru involved in promoting the spirituality of this lineage.
The kind of such selfless service could vary tremendously. It can be the help with office work, organizing events and gatherings, substitute for guru’s obligations of any kinds, promotion of the spiritual lineage in various ways or simply working in the garden or even cooking. Any selfless service of helping a Kaula Tantra guru is sign of gratitude towards Tantric deities.
Indian spirituality calls such actions Karma Yoga. However for the sake of specificity of Tantric tradition, Karma Yoga can be called Karma Tantra. A Tantra aspirant should not hesitate to serve a Tantric guru. On seeing things beyond their surface, the selfless service done to a Kaula guru or an organization supporting this spirituality is serving own personal spiritual growth and aspirations. The proximity with a guru is always inspiring and spiritually uplifting.
This idea was well described mainly in Yoga traditions; there are no reasons to believe that in Tantra as spirituality the concept might be different. A Karma Tantric gives selfless service without expecting any reward. No spiritual person should be under the impression of loosing anything by serving a Kaula Tantra guru. The merits are not lost if guru does not meet the right standard of earthy behaviour (as it might happen with anyone having a human form) because gods keep accounts of merits accumulated by selfless service.
Service to a right cause is always above serving any human being. By making first steps of egoless acts selfless people attract the right circumstances to evolve in the direction envisaged. I would not hesitate to recommend to anyone of doing selfless service. Soon a Karma Tantric will notice how real spiritual progress occurs.