Only one person has to sign a promissory note for it to be legally binding: the maker, meaning the borrower who is promising to pay. Under the Uniform Commercial Code, the note is enforceable once the maker signs it, states an unconditional promise to pay a specific amount, and sets a time for payment.1Legal Information Institute (LII). UCC 3-401 Signature Co-signers, guarantors, witnesses, and notaries can appear on the document too, but none of them are required for the note itself to work.
The Maker Is the One Required Signer
The maker is the borrower, and the maker’s signature is what turns the document from a piece of paper into a binding obligation. The UCC is explicit: a person cannot be held liable on a promissory note unless they signed it, or unless an authorized agent signed on their behalf.1Legal Information Institute (LII). UCC 3-401 Signature No signature from the maker, no enforceable note.
The note should identify the maker by full legal name as it appears on government-issued identification, along with the maker’s address, the principal amount, the interest rate, the repayment schedule, and what happens in a default. If the maker is a business entity, extra rules apply, and those are covered further down.
Does the Lender Have to Sign?
No. The payee — the lender or person receiving payment — does not have to sign for the note to be enforceable. The reason is structural: the promissory note is the maker’s promise to pay. The payee isn’t promising anything; they’re simply named in the document as the party entitled to receive the money.
Some lenders sign anyway. A payee’s signature can help show that both sides agreed to the specific terms, which is useful if a dispute later arises over the interest rate or payment schedule. In certain states or for certain loan types, a lender’s signature is customary. But legally, the note works without it. The payee’s real leverage comes from holding the note and having the right to enforce it.
Co-Signers and Guarantors
When the maker’s credit or income doesn’t satisfy a lender on its own, a second person is often brought in. There are two roles that look similar but carry very different risk.
Co-Signers
A co-signer signs the note alongside the maker and takes on equal responsibility for the debt from day one. If the maker misses a payment, the lender can pursue the co-signer immediately, without first trying to collect from the maker. The loan’s payment history appears on the co-signer’s credit report as if they had borrowed the money themselves. Late payments by the maker damage the co-signer’s credit score, and a default can lead to lawsuits, wage garnishment, or other collection actions against the co-signer directly.2Federal Trade Commission. Cosigning a Loan FAQs
Co-signing is not a character reference or a formality. It’s a binding commitment to pay someone else’s debt if they don’t. Before co-signing anything, assume you’ll be the one making the payments.
Guarantors
A guarantor also agrees to cover the debt if the maker defaults, but with one important difference: the lender generally has to try to collect from the maker first before turning to the guarantor. That secondary position gives a guarantor a layer of protection a co-signer doesn’t have. Guarantors appear more often in commercial lending and lease agreements than in consumer loans.
The distinction matters most when a payment is missed. On a co-signed note, the lender can call the co-signer the same day. With a guarantor, the lender usually has to exhaust efforts against the maker first. Some guarantee agreements change that default rule, so read the specific language before signing.
Signing on Behalf of a Business
When a corporation, LLC, or partnership borrows money, a person still has to pick up the pen. That person needs actual authority to bind the entity, typically an officer, managing member, or partner authorized by the organization’s governing documents. Lenders often ask for proof, such as a board resolution or an operating agreement provision naming who can sign financial documents on the entity’s behalf.
How the signature is formatted matters. Under the UCC, if the signature clearly shows it was made in a representative capacity on behalf of an identified organization, the individual signer is not personally liable on the note.1Legal Information Institute (LII). UCC 3-401 Signature If the signature is ambiguous, say “John Smith” with no mention of the company, the signer can end up personally on the hook. The safe format is something like “John Smith, President of ABC Corp, on behalf of ABC Corp.” Sloppy signature blocks have created personal liability for owners who never intended to guarantee the debt.
Personal Guarantees
Even when a business entity is the maker, lenders often require the owner to sign a separate personal guarantee. This can be its own document or a clause inside the note, and it commits the owner to repay from personal assets if the business cannot. Small business loans and startup financing almost always include one, because the business itself may not have enough assets or credit history to secure the loan on its own.
Signing a personal guarantee strips away the liability protection an LLC or corporation would otherwise provide for that specific debt. If the business folds and can’t pay, the lender can pursue the owner’s personal bank accounts, property, and other assets. Treat a personal guarantee with the same seriousness as co-signing.
Witnesses and Notaries
Neither a witness nor a notary is required for a standard promissory note to be legally binding, but either can strengthen the document if it’s ever challenged.
A witness observes the signing and can later testify that the maker actually signed and appeared to do so voluntarily. The most useful witnesses are disinterested parties who have no financial stake in the transaction. A family member of the lender carries less weight as a witness than an unrelated third party. Two witnesses is common practice, though one is generally enough.
A notary public goes further by verifying the signer’s identity through government-issued identification, confirming the signature is voluntary, and completing a certificate with an official seal.3American Society of Notaries. Your Basic Duties as a Notary Public Notarization doesn’t change the legal effect of the note, but it makes it much harder for a signer to later claim they never signed or were coerced. For larger loans between private parties, the small fee is usually worth it.
What Your Signature Actually Commits You To
Whether you sign as the maker, a co-signer, a guarantor, or a personal guarantor for a business, your signature creates a binding obligation on the note’s specific terms. Those terms usually cover the principal, interest rate, payment schedule, late fees, and what happens on default. Saying later that you didn’t read or understand the terms is not a defense if you’re sued for nonpayment.
The consequences of default reach past the immediate debt. A missed payment can damage your credit score, and prolonged default can lead to lawsuits, wage garnishment, or seizure of collateral if the note is secured by property. For co-signers, those consequences arrive even though someone else borrowed the money. Before signing a promissory note in any capacity, read every provision, pay close attention to the default, acceleration, and late-fee sections, and make sure you can live with the worst-case scenario.