Your client (who has been a client for many years) is an acc…

Your client (who has been a client for many years) is an accrual method taxpayer.  He received $5,000,000 today (from a person not his employer) for engineering design and supervision work to be performed ratably over the next 36 months.  Work will begin September 1, 2025.  Advise him regarding the U.S. income tax consequences of the receipt.