Short answer from a Jain view:

• The soul (jiva) is bound by karma and undergoes many lives in the mortal world until it is purified completely.
• Moksha (liberation) happens when all karmic bonds are shed. At that moment, the soul is no longer in a body and does not wander in the mortal world anymore.
• After moksha, the liberated souls reside in Siddhashila, a realm at the very top of the universe. They are perfectly pure, omniscient, and free; they do not need a body or a journey to travel anywhere.

So the apparent “chicken-egg” worry goes away once you keep the sequence straight: 1) A soul is bound by karma and takes birth in a body. 2) Through right conduct, right knowledge, and right faith (and other purifying practices in Jainism), karma is gradually burnt off. 3) When all karmic bonds are shed, the soul attains kevala jnana and is released from the cycle of birth and death. 4) The liberated soul remains in Siddhashila, not in the mortal world, because there is no longer any karma binding it to rebirth in a body.

Key points to clarify common confusions:

• Siddhashila is the abode of all liberated souls after moksha; it is not a place you arrive at while still in a body.
• Liberation is the removal of all karma, not a gradual “one more trip” in the mortal world. So there is no need for the soul to travel to a higher realm after shedding karma—liberation is the final state.
• Different Jain traditions describe the details a bit differently, but the core idea remains: the jiva becomes free from bonds and then resides in Siddhashila.

If you’d like, I can summarize how the Digambar and Śvetāmbara views differ on the final stages of liberation, or provide a brief sutra-stotra reference to illustrate the concept in Jain scriptures.