The IRS pays taxpayers interest on refunds, with several complex rules about how much and under what circumstances. The rules change slightly during periods with a Presidential emergency declaration, such as that arising from the Covid-19 pandemic. However, all of that is complicated further if the taxpayer's return is not "processible" as filed or if the taxpayer requests an extension to delay the filing date even further than the automatic extension under the emergency declaration. The interaction between all of the relevant provisions is complicated.