Promissory Note in Business Acquisitions: What It Is and What to Include

By Charlie Brennan • Published June 22, 2026 • Updated June 27, 2026 • Educational content only — not financial, legal, or tax advice.

A promissory note is the legal document that records a debt obligation. In a business acquisition, it's the instrument the buyer signs to formalize seller financing — a written promise to pay the seller a specified amount, on a specified schedule, at a specified interest rate. Without a properly drafted promissory note, there's no enforceable debt instrument, and the seller has no legal basis for collection.

What a Promissory Note Must Include

Secured vs. Unsecured Notes

A promissory note can be unsecured (based solely on the buyer's promise to pay) or secured by a lien on business assets. Sellers should almost always insist on a secured note backed by a UCC financing statement filed with the state — this gives the seller a perfected security interest in business assets, allowing them to seize assets in the event of default. An unsecured note requires a lawsuit and judgment before any collection can proceed.

If there's also an SBA loan, the bank's lien is senior — the seller's security interest is subordinate. But a subordinate lien is still meaningfully better than no lien.

Standby Provisions

When SBA financing is involved, the SBA requires the seller note to be on full standby for 24 months — no principal or interest payments from the business to the seller during that period. This standby requirement is memorialized in the promissory note itself and in a separate standby agreement signed at closing.

Promissory Note vs. Seller Note

These terms are used interchangeably. "Seller note" typically refers to the concept of seller-financed debt in a deal; "promissory note" refers to the specific legal document recording that debt. The seller note is evidenced by a promissory note. Both terms appear in deal negotiations — they mean the same thing in context.

Deal-Model Context

A promissory note is the debt instrument that records the borrower's obligation to pay. In acquisitions, it often documents seller financing, standby debt, deferred payments, or a buyer note used to bridge a funding gap.

In the model, the note affects both cash at closing and future debt service. Record principal, interest rate, amortization, maturity, payment frequency, standby period, collateral, guarantees, default rights, and whether payments are subordinate to bank debt.

Buyer Diligence Questions

Diligence should include how the note interacts with lender requirements. An SBA lender may require standby terms, subordination, or limits on seller-note payments. A seller may request collateral or a personal guarantee in exchange for carrying paper.

This term connects to seller financing, seller notes, SBA loans, and DSCR. Ask whether the note is secured, whether it can be prepaid, what happens after default, and whether its payment schedule leaves enough cash for operations.

Practical Review Checklist

Before relying on Promissory Note in Business Acquisitions: What It Is and What to Include in an acquisition model, turn the term into a written assumption. State what source document proves it, what dollar amount or risk category it changes, and whether it affects purchase price, cash at closing, debt service, working capital, legal exposure, or post-close operations. That step makes the concept auditable instead of merely descriptive.

For buyer diligence, collect at least one primary source document, one seller explanation, and one downside case. If the source document is missing, keep the assumption out of the base case. If the downside case changes DSCR, working capital, customer retention, or transition risk enough to threaten closing, address it through price, seller financing, escrow, earnout, indemnity, or a closing condition.

When using AcquireCalc, enter the verified number first, then test the seller's number and a conservative number. The spread between those cases shows whether Promissory Note in Business Acquisitions: What It Is and What to Include is a minor definition, a negotiation point, or a risk that should change the structure of the deal.

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Charlie Brennan

Studied M&A deal structures by analyzing 50+ business acquisition opportunities, with a focus on valuation, financing terms, seller motivations, and operational risk. Built practical acquisition tools for business buyers.