The spread of misinformation has become a global issue with potentially dire consequences. There has been debate over whether misinformation corrections (or" fact-checks") sometimes" backfire," causing people to become more entrenched in misinformation. While recent studies suggest that an overall" backfire effect" is uncommon, we found that fact-checks were more likely to backfire when they came from a political outgroup member across three experiments (N= 1,217). We found that corrections reduced belief in misinformation; however, the effect of partisan congruence on belief was 5x more powerful than the effect of corrections. Moreover, corrections from political outgroup members were 52% more likely to backfire–leaving people with more entrenched beliefs in misinformation. In sum, corrections are effective on average, but have small effects compared to partisan identity congruence, and sometimes backfire–especially if they come from a political outgroup member. This suggests that partisan identity may drive irrational belief updating.