Thank you for that quote, but you didn’t read far enough.
Amounts paid in 2018 or 2019 after filing an original 2017 tax return and before the last day to file a timely Form 1040-X for the 2017 tax year are treated as a casualty loss on a timely filed Form 1040-X for the 2017 tax year (under a special rule applicable for repairs to deterio- rating concrete foundations.
If you paid for repairs in 2018 or 2019, you take the casualty loss by filing an amended 2017 tax return. Publication 547 has not been revised for 2020 tax returns yet, but I would assume that the same rules would apply, if you paid expenses in 2020 for deteriorating concrete repairs, you would take the casualty lost by filing an amended 2017 return, not on your 2020 return. An amended 2017 return must be filed by April 15, 2021.
