I am having same problem getting IRS to accept the qualified contribution at 100% of AGI.  They first denied on notice dated in Sept of 2021. We promptly responded with worksheets, etc and a printed copy of Sch A showing the election on the dotted line.  They didn't respond to our reply until March of 2022 and that was only to inform us that they needed more time.  Now on June 6, 2022 their response was that there decision stands.  (effectively limited to 60% of AGI) I have noticed several suggestions to amend the return to get this done.  Can this election be made on an amended return after the extended due date of the original return?