Q. Where is this stated in the IRS rules that it has to be the same year?
A. IRS Publication 970, which says, in part:
"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"
https://www.irs.gov/pub/irs-pdf/p970.pdf
Also, see previous discussions on this topic:
https://ttlc.intuit.com/community/college-education/discussion/529-provider-distributed-funds-on-12-...
https://ttlc.intuit.com/community/college-education/discussion/i-took-a-529-distribution-in-2021-for...
https://www.savingforcollege.com/article/timing-of-529-plan-distributions-must-match-qualified-expen...
