In the next life. Therefore someone you encounter in this life is paying for the bad karma incurred from a previous life. According to the Brahma Sutras "Each soul is responsible for its own fate" but the soul is reincarnated from one earthly life to the next. So someone suffering in this life is deserving of it.
The fact is this thought process has caused large parts of Hindu society to be indifferent to the suffering of the poor. Mother Teresa in Calcutta was Catholic, not Hindu. Indeed, Christianity changed Rome (and subsequently Western Europe) from a society that valued and taught contempt for the poor and thought of compassion as a weakness to be avoided. Christ's ministry changed all that.
From Wikipedia:
Appaya Dikshita, a Saivite theologian and proponent of Siva Advaita, states that Siva (God) only awards happiness and misery in accordance with the law of karma.[5] Thus persons themselves perform good or evil actions according to their own inclinations as acquired in past creations, and in accordance with those deeds, a new creation is made for the fulfilment of the law of karma. Shaivas believe that there are cycles of creations in which souls gravitate to specific bodies in accordance with karma, which as an unintelligent object depends on the will of Siva alone. Thus, many interpret the caste system in accordance with karma, as those with good deeds are born into a highly spiritual family (probably the brahmana caste).In Christianity, you don't have to wait for "millions of rebirths." You can be reborn now, and reap the reward of the heavenly after-life immediately following your death. You are responsible for your own actions. Nothing of a previous life matters. If you are poor, it is not because your reincarnated soul is receiving the effect of the accumulation of bad karma from a previous life. Which if it is leaves one with no reason to intercede in a life gone bad, as why would I want to thwart the payback for the bad karma the soul is receiving from a previous life? That would go against the system.The Vedas tell us that if we sow goodness, we will reap goodness; if we sow evil, we will reap evil. Satguru Sivaya Subramuniyaswami further notes that karma refers to the totality of our actions and their concomitant reactions in this and previous lives, all of which determine our future. The conquest of karma lies in intelligent action and dispassionate reaction. Not all karmas rebound immediately.
...[M]ost Hindus believe in universal salvation: that all souls will eventually obtain moksha, even if it is after millions of rebirths.