Nunc pro tunc
Nunc pro tunc (English translation: "now for then") is a Latin expression in common legal use in the United States, the United Kingdom, and other countries. In general, a ruling nunc pro tunc applies retroactively to correct an earlier ruling.
Nunc pro tunc may apply to "a judgment is entered, or document enrolled, so as to have the same legal force and effect as if it had been entered or enrolled on an earlier day". This type of order originated from the Court of Chancery from 1388. In 1805 the Lord Chancellor, Lord Eldon, said "The Court will enter a Decree nunc pro tunc, if satisfied from its own official documents, that it is only doing now what it would have done then."
Nunc pro tunc may also apply to acts that are allowed to be done after the time legally allotted to carry them out has passed. For example, in the probate of an estate, if real property, such as lands, mineral interests, etc., are discovered after the final decree or order, a nunc pro tunc order can include these discovered lands or assets into the estate and clarify how they were meant to be distributed. Or, when a court clerk makes a clerical error or a mistake on the public record without any legal authority to do so, without a judicial order, or without obtaining consent by the parties involved. A Nunc Pro Tunc corrects the record to accurately reflect judicial proceedings and agreements reached between parties. 
A corporation may have been created by an individual, but since a corporation, in the United States, has the standing in law of a person (although not a natural person), it is possible for its human creator to go bankrupt and for the assets of the corporation to be seized to satisfy unpaid taxes. If someone buys those assets from the tax authority and the corporation shell passed into other hands, it is possible for the person who bought the assets to also buy the corporation shell and, after paying corporate franchise taxes, for that person to claim that the corporation is nunc pro tunc the original corporation with the original assets.
Internal Revenue ServiceEdit
Some taxpayers file returns or other documents with the Internal Revenue Service (IRS) that have the phrase "nunc pro tunc" stamped or written on the face of the return or document. These taxpayers assert that the phrase "nunc pro tunc" has some legal effect in reducing, eliminating, or altering in some way their federal income tax liability or other obligations under the tax laws. According to the IRS, this is considered a "frivolous" argument and is subject to $5,000 fine. Inserting the phrase "nunc pro tunc" or similar arguments on a return or other document submitted to the Service has no legal effect.
A judgment nunc pro tunc is an action by a trial court correcting a clerical (rather than judicial) error in a prior judgment. A nunc pro tunc may be signed even after the trial court loses its plenary power. For appellate purposes, a nunc pro tunc judgment correctly taken ordinarily does not extend appellate deadlines.
In the Catholic Church, a bishop's resignation is often accepted by the Holy See nunc pro tunc, which means it is tentatively accepted, but the Pope needs some time to locate and appoint a replacement for that diocese. The announcement of the new appointment is usually accompanied by actual acceptance of the outgoing bishop's resignation.
- Mozley and Whiteley's Law Dictionary (11th ed.). ISBN 9780406014207. quoted in Emanuele v Australian Securities Commission  HCA 20, (1997) 188 CLR 114 at p. 131.
- Emanuele v Australian Securities Commission  HCA 20, (1997) 188 CLR 114 at pp. 131-132 per Toohey J.
- Donne v Lewis (1805) II Ves Jun 601 at 601; 32 ER 1221 at p. 1222.
- "11 U.S. Code § 363 - Use, sale, or lease of property". LII / Legal Information Institute. Retrieved 2017-09-09.
- "IRS Hones In On High Rollers". Retrieved 2017-09-09.
- "The Truth About Frivolous Tax Arguments Introduction | Internal Revenue Service". www.irs.gov. Retrieved 2017-09-09.
- "Internal Revenue Bulletin No. 2006" (PDF). Internal Revenue Service. April 10, 2006. Retrieved 26 January 2011.