Promissory Notes for Startups: A Founder's Guide

Stop. Is This an Investment or a Loan?

Before you sign anything called a “promissory note,” you need to understand the single most important distinction: are you taking on debt or selling future equity?

A Simple Promissory Note is a loan. It’s an IOU. You borrow money, and you owe that money back with interest by a specific date. The lender does not get ownership in your company. This is pure debt. · A Convertible Instrument (like a SAFE or Convertible Note) is a path to ownership. An investor gives you cash now, and that “investment” converts into company stock during a future funding round.

Startups should almost always raise capital using convertible instruments or priced equity. A simple promissory note is a niche tool for very specific, temporary situations. Confusing the two is a classic—and sometimes fatal—founder mistake.

This guide is about the simple promissory note : when to use this debt instrument, and how to do it without accidentally bankrupting your company.

When to Use a Promissory Note (The Only Real Scenarios)

A promissory note is not a tool for raising a primary funding round (Pre-Seed, Seed, Series A). Using it for that purpose signals to sophisticated investors that you don’t know what you’re doing. It’s a specific tool for a specific job.

Scenario 1: The Insider Bridge Round

This is the most common and legitimate use case. You have a term sheet for your next round, or a lead investor is deep in diligence and has given a verbal commit. But closing the round will take another 2-4 months, and you only have 6 weeks of runway left.

Your existing investors, who are motivated to protect their current investment, might offer a “bridge loan” to get you to the closing. A promissory note is a fast, simple way to document this short-term financing from friendly insiders.

Typical Amount: $100k - $500k, or whatever covers 3-6 months of burn. · Source: Existing investors who have a vested interest in the company’s survival.

Scenario 2: Formalizing a Founder Loan

You need to put $50,000 of your own money into the company to make payroll. A promissory note is a clean way to document that the company owes you, the individual, that money back. This separates the loan from your equity stake and establishes a clear repayment obligation, which is important for clean accounting and for your relationship with co-founders.

Scenario 3: The Early Friends & Family "Round"

You’re raising your first $25k-$100k from non-professional investors who aren't comfortable with the concept of a SAFE. A simple promissory note can feel more familiar to them—it’s just a loan. However, SAFEs are now so common that they are preferable even in this case, as they better align incentives around long-term equity value.

The Two Clauses That Are Instant Deal-Breakers

Most of a promissory note’s terms are negotiable. These two are not. If you see them, you must walk away or demand they be removed. They give a lender the power to unilaterally destroy your company.

Secured Note / Collateral: A secured note pledges company assets (like your IP, customer contracts, or bank accounts) as collateral. If you default, the lender can seize and sell those assets. This is completely unacceptable in early-stage financing. You would be giving one lender the power to liquidate the company, wiping out founders and all other investors. Venture debt must be unsecured. · Payment on Demand / Demand Note: This clause gives the lender the right to demand full repayment at any time for any reason. It’s a loaded gun pointed at your head. A disgruntled lender could call the note and trigger immediate bankruptcy. Never agree to a demand note.

Anatomy of a Founder-Friendly Promissory Note

Every clause in a note matters. Here’s a breakdown of the key terms and what to watch out for. Your goal is to keep it simple, standard, and aligned with your need to preserve cash.

1. Principal Amount and Parties

This is the easy part. Clearly state the lender, the borrower (your company’s legal name, e.g., "Acme Inc."), the exact dollar amount of the loan, and the date.

2. Maturity Date (The Ticking Clock)

This is the repayment deadline. On this date, the principal and all accrued interest are due. A short maturity date is a death trap.

What’s Standard: 12 to 24 months. For a bridge to a priced round, 18 months is a safe bet. · What to Avoid: Anything under 12 months. Fundraising always takes longer than you think. A 6-month maturity date can create a default crisis before you have time to close your next round. If you need a bridge to close a Series A that you expect to take 3 months, ask for a 12 or 18-month maturity date anyway. The buffer costs you nothing and provides critical insurance.

3. Interest Rate

This is the cost of the loan. For startup notes, it should be simple, not compounding.

What’s Standard: 4% to 8% annual simple interest. This is high enough to be a serious return for the lender but not so high that it’s predatory. A $250k bridge on a 12-month note at 6% interest means you'll owe $265,000 at maturity. · Red Flag: Rates above 10% can look predatory. If investors are asking for this, they may be seeing the loan as a distressed debt opportunity rather than a supportive bridge. · A Note on 0% Interest: You can do this for founder or family loans, but be aware of the IRS’s “Applicable Federal Rates” (AFR). If you offer a loan below this rate, the IRS might “impute” interest for tax purposes. Check with your accountant.

4. Repayment Terms

This defines how you pay the money back. There is only one acceptable answer for an early-stage startup.

The Standard: Balloon Payment. The entire principal and all accrued interest are paid in a single lump sum on the maturity date. This preserves your cash for operations. · The Red Flag: Installments. Any clause requiring monthly or quarterly payments is a cash-flow killer. This isn't a mortgage; it's venture debt. Do not agree to it.

5. Default Provisions

This outlines what happens if you miss the maturity date. Lenders deserve protection, but you need room to fix the problem.

What’s Standard: A "cure period" of 30-60 days to resolve the default. After that, a higher "penalty" interest rate (e.g., 10-12%) may apply until the loan is paid. · What to Negotiate For: Always demand a cure period. This prevents the lender from taking immediate legal action the day after you miss the payment. It gives you time to negotiate an extension or find the funds.

Common Founder Mistakes (and How to Avoid Them)

Using it for Your Seed Round: You approach VCs for a $2M seed round armed with a simple promissory note. They will politely decline. Sophisticated investors want equity upside via a SAFE or convertible note, not low-yield debt. · Agreeing to an 8-Month Fuse: You take a bridge with an 8-month maturity, assuming you'll close your next round in 6 months. The round drags on for 9 months. Now you’re in default, giving the lender massive leverage right when you’re trying to close new investors. · Skimming Over the "Security" Clause: You sign a note from a friendly-seeming lender and miss the paragraph that pledges your company's "intellectual property" as collateral. You have just given that lender the right to seize your code if things go wrong. · Ignoring the Relationship Risk: You take $25k from your uncle on a promissory note. When the maturity date arrives, you can’t pay. This isn’t just a default; it’s a potential family crisis. Be brutally honest about the risks with friends and family. · Skipping the Legal Review: "It's a simple, two-page document, I don’t need to pay a lawyer $2,000 to read it." This is how companies die. That $2k fee is the cheapest insurance you will ever buy.

How to Apply This This Week: A Tactical Playbook

If you anticipate needing a bridge loan, don't wait until you have two weeks of cash left. Get ahead of it.

Draft a "Bridge Memo" for Yourself. Before talking to anyone, write a one-page document answering these questions: · How much do we need to reach the next fundraise? Be precise. · What specific milestones will this capital allow us to hit? · What is the status of the next round? (e.g., "Term sheet in hand from Lead Investor X," "3 firms in late-stage diligence"). · What is our updated, conservative timeline for closing the next round? · Draft Your Investor Update Email. When you’re ready to ask, send a clear, transparent message to your existing key investors. Don't sugarcoat the situation. Hi [Investor Name], Quick update: as you know, we're deep in the process for our Series A. The great news is that we have a term sheet from [Firm Name] / [Positive Diligence Signal]. However, the timeline to close is looking longer than our runway allows. We have about 7 weeks of cash left, and we project needing 12-14 weeks to get the round wired. To ensure a smooth closing, we're raising a small bridge round from existing investors via an unsecured promissory note. We're targeting a total of [$300k]. The terms would be an 18-month maturity and a 6% simple annual interest rate. This will give us more than enough buffer to close the A without any business disruption. Are you open to discussing this week? · Call Your Lawyer. Before you send that email, call your counsel. Validate that a promissory note is the right instrument. Have them review your standard note template so it's ready to go. A quick 30-minute call can save you from a major unforced error.