Publication 970 does not specifically say "qualified withdrawal must be in the same calendar year as when the tuition was paid". But it does say:
To determine if total distributions for the year are more or
less than the amount of qualified education expenses, you
must compare the total of all QTP distributions for the tax
year to the AQEE. Page 51
"Multiply the total distributed earnings shown in box 2
of Form 1099-Q by a fraction. The numerator (top
part) is the AQEE paid during the year, and the denominator (bottom part) is the total amount distributed
during the year" Page 52
https://www.savingforcollege.com/article/timing-of-529-plan-distributions-must-match-qualified-expen...
"529 plan distributions must be made during the same tax year that the qualified expenses are incurred. This is not an official IRS rule, but it is implied by published IRS guidance. Tax professionals and other experts agree that 529 plan distributions should match up with qualified expenses."
I find this web site to be one of the most authoritative on 529 plans.
