Cheating is a big sin. What are the punishments for cheating in Islam according to Qur’an and Ahadith? Will this punishment be here or in Hereafter?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Cheating, as the questioner pointed out, is one of the greatest sins.  The Prophet (Sallallahu Alaihi wa Sallam) did not consider the person who cheats to be among the Muslims to be on their way or guidance in having good relations with others, or who deserve advice.

The Prophet (Sallallahu Alaihi wa Sallam) said: “Whoever cheats us is not one of us.” [Reported by Muslim]

The Muslim ruler has to reprimand the person who cheats with what will make him defer from cheating, and punish him until he becomes straight and correct, and he will be an example for others.

This is with regard to his punishment in this world, let alone the punishment that is awaiting him in the Hereafter, if he does not repent or if he is not forgiven by Allah.

It is possible as well that Allah will hasten his punishment to make it happen this world according to his sins.  It is reported in Saheeh Bukhari and Muslim that "Whoever cheats his subjects will not enter Paradise.  And this is his punishment in the Hereafter;” we seek refuge in Allah from that.

Allah knows best.