SAFE (Simple Agreement for Future Equity)

When an investor signs a SAFE, they wire capital to the startup but do not immediately receive shares. Instead, the SAFE 'converts' into equity when a triggering event occurs — most commonly a priced equity round (Series Seed or Series A). At conversion, the SAFE holder receives shares at a price determined by the SAFE's terms: either a valuation cap, a discount rate, or both (whichever gives the investor more shares). Unlike convertible debt, a SAFE has no maturity date, no interest rate, and is not a loan — it is a contractual right to future equity. This makes SAFEs significantly simpler from both a legal and accounting perspective.

The two most important economic terms in a SAFE are the valuation cap and the discount rate. The valuation cap sets a maximum valuation at which the SAFE converts — if the priced round values the company above the cap, the SAFE holder converts at the lower cap price, getting more shares per dollar. The discount rate (typically 15-25%) gives the SAFE holder a percentage discount to the price per share paid by new investors in the priced round. If a SAFE has both a cap and a discount, the investor gets whichever produces more shares. Some SAFEs are uncapped, meaning conversion happens at the discount to whatever the round price is, with no ceiling on the conversion valuation.

The original Y Combinator SAFE (2013) was a pre-money SAFE, where the cap referred to the pre-money valuation and the investor's ownership depended on how many other SAFEs and convertible instruments were outstanding. In 2018, Y Combinator introduced the post-money SAFE, which defines the cap as a post-money valuation. This means the investor knows their exact ownership percentage at conversion regardless of other outstanding SAFEs. For example, a $500K investment on a $5M post-money SAFE cap guarantees 10% ownership. Post-money SAFEs are now the standard, but founders must be careful because stacking multiple post-money SAFEs can lead to significant dilution since each one independently claims its percentage from the cap table.

SAFEs differ from convertible notes in several important ways. Convertible notes are debt instruments — they have a maturity date (typically 18-24 months), accrue interest, and create a legal obligation to repay. SAFEs are equity instruments with no maturity or interest, which means they never come due and there is no risk of default. SAFEs are typically one-page documents with minimal legal costs, while convertible notes require more negotiation around debt terms. However, SAFEs offer less protection for investors since there is no maturity deadline forcing a conversion or repayment event. The number of diluted shares outstanding increases when SAFEs convert, which affects every existing shareholder.