What if someone didn't pay zakat for 2 years. Should he/she consider paying for the 2 years. What are the rules/punishment that he/she will receive from Allah. What does Quran say about those persons?
Jazakum Allah Khayraa
A person who denies Zakah is considered a disbeliever. First there must be an attempt to correct him. If he insists on his denial, he must be killed for disbelief. However, an allowance must be given to the person who recently converted to Islam on account of his ignorance of its principles. He must be directed until he abides by and acknowledges the giving of Zakah. As for one who though acknowledges the obligation to pay Zakah but abstains from giving it, he only incurs sin without being considered a disbeliever. Rather he should be given a discretionary punishment and forced by the ruler to pay Zakah. If a powerful group of people abstains from paying Zakah though acknowledging its legality, they must be fought until they pay it. This is confirmed by Abu Hurairah's narration that, "When the Messenger of Allah (peace be upon him) deceased and Abu Bakr was appointed Caliph, some Arab tribes became apostates.
Umar said to Abu Bakr, "Why would you fight these people while Allah's Messenger (peace be upon him) said: I have been directed to fight against people till they testify that there is no god but Allah. Whoever professes it is granted full protection of his property and life except for a right cause and his (other) affairs rest with Allah?" Upon this Abu Bakr said, 'By Allah, I would definitely fight against those who make a difference between Prayer and Zakah, for it is the obligation upon the rich. By Allah, I would fight against them even if they withheld a cord (used for hobbling the feet of a camel) which they used to give to Allah's Messenger (peace be upon him) (as Zakah).'Umar said, 'Then I became convinced that Abu Bakr was right.'"
Abu Hurairah (may Allah be pleased with him) also reported that Allah's Messenger (peace be upon him) said, "The owner of gold or silver who does not pay the poor due (Zakah) will have a bitter punishment on the Day of Resurrection. Plates of fire will be beaten out for him; these will then be heated in the fire of Hell and his sides, forehead and back will be cauterized with them. Whenever these cool down, (the process will be) repeated throughout a day whose extent will be fifty thousand years until Judgment is pronounced among the servants, and he sees whether his path is to take him to Paradise or to Hell."
Abdullah bin Masud (may Allah be pleased with him) reported Allah's Messenger (peace be upon him) as saying, "There is no owner of property who does not pay Zakah but it (his property) will turn into a bald snake and enclose his neck. (The Prophet, peace be upon him) then recited, 'And let not those who covetously withhold of the gifts which Allah hath given them of His Grace, think that it is good for them: nay, it will be the worse for them; soon shall the things which they covetously withheld be tied to their necks like a twisted collar on the Day of Judgment.'" (Surah Aal `Imran 2:180).
`Ali (may Allah be pleased with him) reported, "Allah's Messenger (peace be upon him) cursed the one who accepts or gives interest, the one who witnesses to it and the one who records it; (and cursed) the female tattooer and the woman who gets herself tattooed; (and also cursed) the one who withholds Sadaqah (Zakah), the Muhallil (the one who marries an irrevocably divorced woman then divorces her with the aim to return to her previous husband) and the Muhallal Lahu (the one who irrevocably divorces his wife and gets her married to another then divorced from another man in order to marry her again."
Yes, someone should pay your zakat that they didn't pay - asap. Generally speaking Allah will wait your taubah until you're dead, this is Allah's rahma. Dead can happen anytime, If Allah don't want to give more rahma, Allah won't give someone a chance to repent.