Unpaid principal balance (UPB) is the outstanding principal still owed on a loan, excluding accrued interest, fees, and advances. It is the headline figure on a loan tape and the starting point for pricing a note — though a buyer prices to collateral and recovery, not to UPB.
UPB anchors the conversation, but the sale price reflects the collateral value and recovery path, not the face balance. A well-secured loan can price near UPB; an under-secured one prices below it. See how buyers price a CRE loan.
No — the payoff also includes accrued interest, fees, and advances; UPB is principal only.
Rarely — non-performing loans are priced to collateral and recovery path, often below UPB.
It is a core field — see the loan-tape checklist.