If you’re raising a pre-seed or seed round, you’ve likely come across two instruments founders use constantly: SAFEs and convertible notes. Both let you raise money now and defer setting a formal valuation until later. But they work differently, carry different risks, and the differences matter more than most founders realize — often not until it’s time to close a round, or negotiate the next one.
Here’s a high-level look at how each works, where they diverge, and why the choice deserves more thought than founders often give it.
The Basic Idea Behind Both Instruments
Priced equity rounds require agreeing on a company valuation, which is difficult to do fairly at the earliest stages when there’s little data to base it on. SAFEs and convertible notes solve this by letting investors put in money now, with the right to convert that money into equity later — usually at your next priced round — without pinning down a valuation today.
Both instruments typically include investor protections designed to reward early investors for taking on risk before the company has a track record. Both SAFEs and convertible notes commonly include a valuation cap and discount, which helps determine a favorable conversion price later. They diverge in their legal structure, and that structural difference has real consequences for founders.
What Is a Convertible Note?
A convertible note is structured as debt. It’s a short-term debt instrument from the investor to the company, and unlike a SAFE, it can accrue interest at an interest rate that is often around 4% to 8% annually and includes a maturity date, often 18-24 months, by which it must convert or be repaid.
Because a convertible note is technically debt, it creates debt obligations and interacts with your company’s finances and legal risk profile differently than equity does, including how it appears on the balance sheet. This has implications both for how your company is perceived and for what happens if things don’t go according to plan. The tax treatment matters too: interest may be tax-deductible for the company, while note holders can face ordinary-income tax from accrued interest.
What Is a SAFE?
A SAFE (“Simple Agreement for Future Equity”) was created by Y Combinator in 2013 to simplify and speed up early-stage fundraising. A SAFE note is a financial instrument that is neither equity nor debt at signing, but a contractual right to receive equity in the future. Unlike convertible notes, it does not carry interest or maturity date terms and does not create interest accrual.
This structural difference is a big part of why SAFEs have become the default instrument for many early pre-seed and accelerator-backed deals: they tend to involve less negotiation, lower legal costs, and fewer of the pressure points that come with a debt instrument. For safe investors, that also means no interest income and no interest-based tax deductions for the company, while gains on conversion may instead be taxed under capital-gains rules at lower rates depending on the facts.
Why the Difference Matters for Founders
- Timing pressure works differently across the two instruments. Convertible notes have a maturity date, typically 18-24 months, while SAFEs generally do not. Convertible notes accrue interest, and the principal plus accrued amount usually converts into equity in the next financing or at maturity, while SAFEs do not accrue interest or have a maturity date. Founders are often surprised, well into a raise, by how much this distinction shapes their negotiating position later.
- Debt changes your company’s risk profile. Because one instrument is debt and the other isn’t, they can affect your company differently in a downside scenario — including who has priority claims on the company’s assets. This is a meaningful distinction for an early-stage company with limited resources, and it’s not always obvious from the paperwork itself.
- Multiple instruments stack — and founders often lose track of this. It’s common for early companies to raise several rounds of SAFEs or notes from different investors over time, each with different terms. When a priced round finally happens, a future financing round or qualified financing round is often the triggering event for conversion, and that shift can change how new investors and founders experience dilution on the cap table if it hasn’t been carefully modeled in advance. We regularly see cap tables where founders are surprised by how much of the company converts away in this single moment.
- Not all SAFEs are structured the same way. Y Combinator’s standard SAFE has evolved over time, and different versions calculate investor ownership differently. Different SAFE versions can also change how the conversion price is calculated against a future valuation. Using different versions inconsistently across the same fundraising round — or failing to understand how they interact with each other — can result in more dilution than founders expect.
Common Mistakes We See
- Founders modeling each SAFE or note individually, rather than understanding how they combine and convert together
- Overlooking deadline-driven terms until they’re already approaching
- Mixing instrument types across a round without a clear plan for how they’ll interact at conversion
- Using inconsistent templates or versions across the same round
- Bringing in counsel only after a dispute or surprise arises, rather than before signing
Each of these is generally straightforward to catch and correct early — and considerably more difficult and costly to unwind after the fact.
Which Should You Use?
There’s no universal answer. There are a few key differences between safe vs convertible note structures, and the right choice depends on your investor base, with some international investors more familiar or comfortable with convertible notes than SAFEs, your timeline, and the specific terms being offered. Founders often use these instruments to raise capital before a priced equity round or preferred stock financing, without setting a company valuation upfront, and many companies end up using a combination of both at different stages, which makes it even more important to understand exactly how everything will convert and interact before signing anything.
The Bottom Line
SAFEs and convertible notes both let you raise money without agreeing on a valuation upfront, but the structural differences in convertible notes vs SAFEs have real consequences for founders — particularly around timing, risk, and dilution. The details matter, and they’re easy to get wrong without experienced guidance.
If you’re preparing to raise a pre-seed or seed round, it’s worth having your specific instruments and terms reviewed by an attorney and financial advisors before you send them to investors — not after you’ve signed something you don’t fully understand.
This article is provided for general informational purposes and does not constitute legal advice. Every fundraising situation is different, and founders should consult with an attorney before finalizing any fundraising instruments.
