The law if one transgressed the Chazara conditions:[1]

If one heated food on Shabbos in a way that transgressed the Chazara conditions, then at times it is prohibited to eat the food on Shabbos. The following is the law:

If the food was not fully cooked or contains cold liquid: If the food was not fully cooked, or contains cold liquid, then the food may not be eaten by anyone on Shabbos, although it may be eaten by anyone immediately after Shabbos. If, however, the transgressor did so advertently, the food is forever forbidden for him. See Chapter 6 Halacha 25 for the full details of this matter!

If the food is fully cooked and further cooking is beneficial for the owner:[2] If the food is fully cooked and further cooking is beneficial for the owner, then it depends on whether the placing of the food on the fire transgressed a prohibition according to all opinions. If the food was originally on the fire/Blech when Shabbos started and was then removed and the replaced, then it depends on which of the six Chazarah conditions were transgressed and not fulfilled. If the food was still warm and the fire was covered, but the food was put down, or was switched to a different pot, or one did not have intent to return it, then the lack of fulfillment of these conditions do not prohibit the food from being eaten, and it is hence permitted to eat these foods on Shabbos even though they were heated in a forbidden way. If, however, the food was cold, or the fire was not covered, then if the transgression was done Bemeizid, the food is forbidden for everyone to eat until after Shabbos, Kdei Sheyasu. Likewise, if it was removed from the fire before Shabbos, and replaced Bemeizid onto the fire on Shabbos, then it is forbidden to be eaten until after Shabbos, irrelevant to which of the six Chazarah conditions was not fulfilled.[3] If, however, the transgression was done Beshogeig, then it is disputed[4] if the food may be eaten, and practically we rule that the transgressor and his household[5] may not eat the food until enough time has passed after Shabbos for one to be able to have heated it up and received the benefit which he had transgressed. However, all other individuals may eat it even on Shabbos.

If the food is fully cooked and further cooking is detrimental for the owner:[6] If the food is fully cooked and further cooking is detrimental for the owner, then it may be eaten by all people on Shabbos. [This applies even if the food was returned Bemeizid.[7]] [See Q&A regarding if this leniency applies even if the food was cold and became heated.]

Waiting after Shabbos Kdei Sheyasu to eat the food:[8] Whenever the food is prohibited on Shabbos due to transgressing the Chazara laws [as opposed to the cooking laws] and was fully cooked[9], it is only permitted after enough time has passed after Shabbos for one to be able to have heated it up and received the benefit which he had transgressed.[10]

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[1] Admur 253:24; See Piskeiy Teshuvos 253:10

[2] Admur ibid “If one transgressed and returned a pot on Shabbos to an area which (according to all opinions–So rules also Biur Halacha 253 “Veim Hichziru Yisrael” based on M”A 253:14) is forbidden for one to return there, whether this was done advertently [with prior knowledge of the transgression] or was done inadvertently [such as he did not have knowledge of the transgression], [nevertheless] the food is forbidden until enough time has passed after Shabbos for one to be able to have gotten this benefit from the food. However, this only refers to a case that the cooking of the food which was placed on Shabbos caused the food to condense in a way beneficial for the food.”

[3] Pashut; Piskeiy Teshuvos 253 foootnote 95

[4] Admur ibid “[Furthermore] there are opinions which deliberate even when the food that was returned had condensed in a way beneficial for it, if it should be prohibited at all after the fact, if it was done inadvertently, being that the food was already fully cooked [prior to being returned to the fire]. Practically, one may rely on this latter opinion to allow people who the food was not intended to be heated up for, [to eat from it on Shabbos]. However, for [the person himself who returned it to the fire and for] his household members one should not permit [it to be eaten by them], as the food had also been returned to the fire on their behalf.”

[5] Vetzaruch Iyun regarding guests.

[6] Admur ibid “However, if it condensed in a way that was damaging to the food then it is permitted to eat even on Shabbos, as he has received no benefit from the transgression.”; However, see Ketzos Hashulchan 124:21 which does not differentiate in this matter.

Does the above law apply even if the food was cold and became heated? Seemingly this applies even if the food was cold and became heated [and does not contain gravy-see 318:9] nevertheless the Sages did not fine one not to benefit from the heat. However, many Poskim write that any time the food became hotter due to the transgression one cannot benefit from the food even if it condensed in a way detrimental to the owner. [Peri Megadim 253 M.Z. 10 and A.A. 37; Chazon Ish 37:27; Biur Halacha 253 “Lehacheim; Piskeiy Teshuvos 253:10] So is also implied from Admur 318:25 which mentions that if a gentile returned it and the food was cold and became heated then it is forbidden for all people even after it calls down. Admur here does not differentiate between the household and others or Mitztameik Veyafeh Lo and Mitztameik Vera Lo, as he did in the previous Halacha. [See Tehila Ledavid 253:10] This implies that certainly if a Jew returned cold food in a forbidden way and it became heated due to it then the food is forbidden for all. Vetzaruch Iyun Gadol as neither the Ketzos Hashulchan [124:21] nor Kitzur Dinei Shabbos [253:31-33] mention this in their summary and rather simply write that whenever it was fully cooked it is permitted for others.

[7] Kitzur Halachos 253:33

[8] Admur ibid and 318:1

[9] Vetzaruch Iyun if this waiting of “Kdei Sheyasu” applies if the food was not fully cooked and one thus transgressed the cooking prohibitions, in which case we rule that it is permitted immediately after Shabbos.

[10] The reason for not needing to wait Kdei Sheyasu after Shabbos by one who cooked on Shabbos, versus one who simply transgresses Chazarah: The reason why regarding one who transgressed and cooked on Shabbos Beshogeig is not required to wait until enough time passed after Shabbos to have been able to cook it is because [the Sages] only required one to wait this amount [of time] by a gentile which does [a forbidden action] for a Jew, as in such a case if [the Jew] were to be allowed to benefit [from the food] immediately after Shabbos then there is room to worry that he may tell [the gentile] to do so on Shabbos in order so [the food] be ready for him immediately after Shabbos. [The reason that we suspect for this is] because the prohibition against telling a gentile [to do a forbidden action on ones behalf] is considered light in the eyes of people. Similarly, [this decree as well applies] even when a Jew does [a forbidden action] in a case that he started from before Shabbos to do something that was forbidden to be started as was explained in chapter 253 [Halacha 1], as this prohibition too is light in the eyes of people and there is thus worry that one will transgress it in order so [the food] be ready [for him to eat] immediately after Shabbos. Therefore [in the above two cases the Sages] required even others to delay [benefiting from the food] until enough time has passed after Shabbos to have been able to cook it. [The decree even includes other people] due to a decree that [otherwise] one may tell another person to start [cooking it for himself and others] from before Shabbos. However [by other prohibitions done on Shabbos the Sages] were not worried at all that one may tell a Jew to do for him the prohibited action on Shabbos in order for him to be able to benefit from it immediately after Shabbos. Furthermore, [besides for the fact that we do not suspect a Jew of stooping so low to have another Jew transgress for him, even if a Jew were to ask another Jew to do so for him] the Jew would not listen to him being that people do not sin [on behalf of someone else] without self-benefit. [Admur ibid]

[11] Peri Megadim 253 M.Z. 10 and A.A. 37; Chazon Ish 37:27; Biur Halacha 253 “Lehacheim; Piskeiy Teshuvos 253:10

[12] P”M 253 M”Z 10; A”A 37; Biur Halacha “Lehachem”; M”B 253:95; See Chazon Ish 37:27 that is stringent

[13] It is implied from Admur 318:25 that if the food was cold it is forbidden for all people even after it cooled down from its heat received due to the prohibition. This is implied from Admur there which mentions that if a gentile returned it and the food was cold and became heated then it is forbidden for all people even after it calls down. Admur here does not differentiate between the household and others or Mitztameik Veyafeh Lo and Mitztameik Vera Lo, as he did in the previous Halacha. [See Tehila Ledavid 253:10] This implies that certainly if a Jew returned cold food in a forbidden way and it became heated due to it then the food is forbidden for all. Vetzaruch Iyun Gadol as neither the Ketzos Hashulchan [124:21] nor Kitzur Dinei Shabbos [253:31-33] mention this in their summary and rather simply write that whenever it was fully cooked it is permitted for others.