I know it can take up to 16 weeks to process an amended return. The 2018 numbers would be different from what I thought when I filed the extension and paid, because of the 2017 change. If I file my extended 2018 return now, it will line up with my already filed 2017 but not the new numbers in the amended. The IRS might get the amended processed before the Oct 15 2019 deadline for this year's return, in which case I can file a 2018 return based on amended 2017, but if not, should I file 2018 based on the original processed return and then have to amend 2018 too? I would probably have to overpay if I do that.
