The Static-99 is an actuarial risk prediction instrument designed to estimate the probability of sexual and violent reconviction for adult males who have already been charged with or convicted of at least one sexual offense against a child or a non-consenting adult. This instrument may be used with first-time sexual offenders.

This instrument cannot be used to assess females, young offenders (those having an age of less than 18 years at the time of release) or offenders who have only been convicted of prostitution-related offenses, such as pimping, sex in public locations with consenting adults, or possession of adult pornography/indecent materials. The Static-99 is not recommended for use with those who have never committed a sexual offense, nor is it recommended for making recommendations regarding the determination of guilt or innocence in those accused of a sexual offense. The Static-99 is not appropriate for individuals whose only sexual crime involves consenting sexual activity with a similar age peer (e.g., statutory rape), where the ages of the perpetrator and the victim are close and the sexual activity was consensual. The Static-99 applies where there is reason to believe a sex offense has occurred with an identifiable victim. The offender need not have been convicted of the offense. The original samples used to create this instrument contained a number of individuals who had been found Not Guilty by Reason of Insanity and others who were convicted of non-sexual crimes, but in all cases these offenders had committed real sex crimes with identifiable victims. (Static-99R Coding Rules, Revised)

The Static-99 is not applicable to offenders who have had more than 10 years at liberty in the community without a sexual offense before they were arrested for their current non-sex offense if they have not committed a new serious or violent offense of any kind after release in the community for 10 years. A Static-99 score is marked as "Incomplete" if the scorer did not have information about one or more risk factors on the risk assessment instrument (e.g., was the victim a relative? a stranger?) An offender with an incomplete score may be at higher risk to re-offend than the incomplete score indicates.