Can a seller refuse to subordinate their vendor take-back note to my bank loan?

Yes. Subordinating a vendor take-back note behind a buyer's bank loan is not required by law — it is a negotiated arrangement, usually documented in a subordination or intercreditor agreement, that a buyer's bank will often insist on so its own security ranks ahead of the seller's in the event of a default or insolvency. A seller is free to decline to subordinate, just as a bank is free to decline to lend without it.

If the seller refuses and the bank's financing genuinely depends on that subordination, the practical consequence is usually that the bank will not lend on the proposed structure, requiring the buyer to either restructure the financing, reduce the seller-financed portion, find a different lender with different requirements, or renegotiate the vendor take-back terms with the seller. Subordination is really a three-way negotiation among buyer, seller, and lender rather than something the buyer can simply impose on the seller, so this needs to be worked out early, before the buyer is relying on a specific financing structure that assumes the seller's cooperation.