Question

Kimberly originally filed her 2017 return on February 19, 2018 under ordinary circumstances, what is the last day she can file an amended 2017 return

Answer 1

If a refund is expected on an amended return, Kimberly  must file the return within three years of the due date of the original return, or within two years after the date they paid the tax, whichever is later.
Returns filed before the due date  are considered filed on the due date (15 April, 2018)
Last day to file an amended 2017 return	15-Apr-21
If the amended current year return indicates the Kimberly owes money, file Form 1040X and instruct the Kimberly to pay the amount by the April due date to avoid interest and penalties.
Last day to file an amended 2017 return	15-Apr-18