The tax filing deadline isn't necessarily the final act for a tax year. In certain situations, events or other circumstances make it important to review the tax positions taken on a return and make changes to it via an amended return. This year in particular warrants a review of returns filed for 2018 and 2019. And even after the 2020 returns are filed, it may be desirable in the future to amend previous returns. These reviews are triggered in part by changes in tax rules related to COVID-19, various natural disasters, and other reasons.