A false accusation is a claim or allegation of wrongdoing that is untrue and/or otherwise unsupported by facts. False accusations are also known as groundless accusations or unfounded accusations or false allegations or false claims. They can occur in any of the following contexts:
When there is insufficient supporting evidence to determine whether an accusation is true or false, it is described as "unsubstantiated" or "unfounded". Accusations that are determined to be false based on corroborating evidence can be divided into three categories:
A false allegation can occur as the result of intentional lying on the part of the accuser; or unintentionally, due to a confabulation, either arising spontaneously due to mental illness or resulting from deliberate or accidental suggestive questioning, or faulty interviewing techniques. In 1997, researchers Poole and Lindsay suggested that separate labels should be applied to the two concepts, proposing that the term "false allegations" be used specifically when the accuser is aware that they are lying, and "false suspicions" for the wider range of false accusations in which suggestive questioning may have been involved.
When a person is suspected of a wrongdoing for which they are in fact responsible, "false accusation may be used to divert attention from one's own guilt". False accusation may also arise in part from the conduct of the accused, particularly where the accused engages in behaviors consistent with having committed the suspected wrongdoing, either unconsciously or for purposes of appearing guilty.
Additionally, once a false accusation has been made – particularly an emotionally laden one – normal human emotional responses to being falsely accused (such as fear, anger, or denial of the accusation) may be misinterpreted as evidence of guilt.
A false accusation of rape is the intentional reporting of a rape where no rape has occurred. It is difficult to assess the prevalence of false accusations because they are often conflated with non-prosecuted cases under the designation "unfounded". However, in the United States, the FBI Uniform Crime Report in 1996 and the United States Department of Justice in 1997 stated 8% of rape accusations in the United States were regarded as unfounded or false. Studies in other countries have reported their own rates at anywhere from 1.5% (Denmark) to 10% (Canada). Due to varying definitions of a "false accusation", the true percentage remains unknown.
A false allegation of child sexual abuse is an accusation that a person committed one or more acts of child sexual abuse when in reality there was no perpetration of abuse by the accused person as alleged. Such accusations can be brought by the victim, or by another person on the alleged victim's behalf. Studies of child abuse allegations suggest that the overall rate of false accusation is under 10%, as approximated based on multiple studies. Of the allegations determined to be false, only a small portion originated with the child, the studies showed; most false allegations originated with an adult bringing the accusations on behalf of a child, and of those, a large majority occurred in the context of divorce and child-custody battles.
Research by the Workplace Bullying Institute, suggests that "falsely accused someone of 'errors' not actually made" is the most common of all bullying tactics experienced, in 71 percent of cases. For example: In 2018 Bhatia, Navin K. had framed past employees of theft and fraud and forged documents then making false accusations against the employee that had recently quit to make up lost revenue. Bhatia was never charged but has been fired and is no longer with the company. 
The case has been made that diagnoses of Münchausen syndrome by proxy, that is harming someone else in order to gain attention for oneself, are often false or highly questionable.
In 1999, Pathe, Mullen and Purcell wrote that popular interest in stalking was promoting false claims. In 2004, Sheridan and Blaauw said that they estimated that 11.5% of claims in a sample of 357 reported claims of stalking were false.
Rage by a narcissist is directed towards the person that they feel has slighted them. This rage impairs their cognition, therefore impairing their judgment. During the rage, they are prone to shouting, fact distortion and making groundless accusations.
Psychological projection can be utilized as a means of obtaining or justifying certain actions that would normally be found atrocious or heinous. This often means projecting false accusations, information, etc., onto an individual for the sole purpose of maintaining a self-created illusion.