The Y Combinator SAFE: A Founder's Clause-by-Clause Guide

The SAFE — Simple Agreement for Future Equity — is the shortest financing document most founders will ever sign. It runs about seven pages, has no interest rate, no maturity date, and no repayment obligation. It also converts into the priced round that will define your company's cap table for the next decade. Every word in it matters.

This guide walks through a standard post-money Y Combinator SAFE the way founders actually need to read it: clause by clause, in plain English, with the numbers and edge cases that determine whether you end up with the ownership you thought you had. The template we reference here is the version most seed-stage US startups sign today — one page of legend, one page of terms, and five pages of definitions and boilerplate.

A SAFE is a contract to issue future stock. When an investor wires you the Purchase Amount, they do not become a stockholder. They receive a piece of paper — the SAFE itself — that says: "if you raise a priced round, sell the company, or dissolve before those things happen, I get either shares or my money back, on these terms."

That is the entire mechanism. There is no debt. Nothing accrues. Nothing matures. If none of the three trigger events ever happens, the SAFE sits on your cap table forever. This is why SAFEs are simple to sign and dangerous to sign carelessly: the founder-friendliness of the document at signing is the reason its consequences at conversion catch so many teams by surprise.

The document has four operative sections and a fifth section of representations. We will take them in the order they appear.

The block of capitalized text at the top of the SAFE is a securities-law legend. It states that the SAFE has not been registered under the Securities Act of 1933 and cannot be freely resold. This is not negotiable and is not decorative — it is what makes the sale of an unregistered security to your investor legal under a Regulation D exemption. Investors must be accredited (in almost every deal you will see), and the SAFE must not be publicly offered.

Below the legend, the header names the parties and the money:

XYZ Corporation — this must be a Delaware C-corporation. SAFEs do not work cleanly with LLCs, S-corps, or foreign entities because the conversion mechanics assume a Delaware corporate stack with authorized preferred stock. If you are an LLC, convert before you sign a SAFE.

Investor — the individual, fund, or entity purchasing the SAFE. Fill this in with the actual signing entity, not a placeholder or a fund's marketing name.

Purchase Amount — the dollars wired. This is the only number the SAFE cares about for conversion math. If the investor promises $250,000 but wires $200,000, the SAFE converts on $200,000.

Effective Date — the date money is received. Not the date of signing. Get the wire in before you countersign or clarify in an email that the Effective Date is the wire date.

Everything in a SAFE is triggered by one of three events. If none of them happens, the SAFE never converts. This is the section founders should reread every time a financing, acquisition, or wind-down comes into view.

The most common conversion path. When you raise a priced preferred round after signing the SAFE, the SAFE converts into preferred stock automatically at closing. There are two possible outcomes:

1. Priced round below or equal to the Valuation Cap. The SAFE converts at the priced round's price per share. The investor gets Standard Preferred Stock — the same series and terms as the new money. 2. Priced round above the Valuation Cap. The SAFE converts at the Safe Price — the price implied by dividing the Valuation Cap by the Company Capitalization. The investor gets Safe Preferred Stock, a shadow series that mirrors Standard Preferred economically but exists as a separate series solely because it was issued at a lower price per share.

The SAFE says the Investor "will execute and deliver to the Company all transaction documents related to the Equity Financing." This is what makes a SAFE conversion clean: the SAFE holder must sign the voting agreement, IRA, ROFR/co-sale, and any drag-along that the new preferred holders sign. Do not accept side letters that carve SAFE holders out of the drag-along without your counsel's review.

The document guarantees "customary exceptions" and "limited representations and warranties" for the SAFE holder. This is standard and should not be renegotiated. If a SAFE investor is asking for reps and warranties in the SAFE itself, something is off.

If you sell the company or go public before raising a priced round, the SAFE holder gets to choose:

1. Cash back — the Purchase Amount, paid at closing. 2. Common stock — a number of shares equal to Purchase Amount divided by the Liquidity Price. Liquidity Price is defined off the Liquidity Capitalization (see Section 2), which excludes unissued option pool but includes the SAFE itself and all other SAFEs and convertibles.

Founders often assume investors will take the cash. In practice, if the sale price is meaningfully above the Valuation Cap, sophisticated investors take the stock — that is the entire economic point of investing early. Model both outcomes when you sign an LOI: the SAFE holder's optionality is real dilution to Common.

There is one important sub-clause: if the company cannot pay all Cash-Out Investors in full, the SAFEs share pro rata, and the shortfall automatically converts to Common. And in a Change of Control structured as a tax-free reorganization, the board can reduce cash payments pro rata to preserve tax treatment, converting the difference to stock. Both are protective of the transaction, not the SAFE holder, and both are market.

If the company dissolves before a priced round or sale, the SAFE holder is paid the Purchase Amount before any Common holder receives a distribution. If assets are insufficient, the SAFEs share pro rata against each other. Common gets nothing until SAFEs are paid.

This is why SAFEs behave a little like preferred stock even before conversion: in a wind-down, they have a liquidation preference equal to the Purchase Amount. Founders whose companies do not raise a priced round and do not sell should assume any residual cash goes to SAFE holders first.

The SAFE terminates in two ways: it converts into stock (Sections 1(a) or 1(b)(ii)), or it is paid out in cash (Sections 1(b)(i) or 1(c)). Until one of those happens, the SAFE lives on the cap table indefinitely. There is no maturity date. There is no expiry. This is one of the largest philosophical differences between SAFEs and convertible notes, and founders should track outstanding SAFEs on their cap table with the same discipline as issued equity.

The Events section is short because the math is buried in the definitions. Read this section slowly.

These are the two conversion denominators and they behave very differently.

Company Capitalization is used to calculate the Safe Price when a priced round happens. It includes all outstanding shares on an as-converted basis, all vested and unvested options, and — critically — all shares reserved for future grant under the option plan, including any increase adopted in connection with the Equity Financing. It excludes the SAFE itself, all other SAFEs, and convertible promissory notes.

What this means in practice: the option pool refresh that the new lead requires you to adopt at the priced round is included in Company Capitalization. That refresh dilutes the founders, not the SAFE holders. This is the post-money SAFE behavior founders miss most often. If you sign $2M of SAFEs at a $10M cap and later raise Series A with a 15% post-money option pool, the pool comes out of founder equity, and the SAFE holders convert into their full 20% at post-money math.

Liquidity Capitalization is used to calculate the Liquidity Price in a sale before a priced round. It includes all outstanding capital stock and vested options, plus the SAFE itself and all other SAFEs and convertibles — but it excludes unissued option pool. The exclusion of unissued pool is investor-friendly here (larger denominator would dilute their conversion less), but the inclusion of other SAFEs is founder-friendly because it caps aggregate SAFE dilution to the sale.

Circle both definitions on the printed page. If your counsel proposes edits, understand which denominator they are changing.

The Valuation Cap is the ceiling on the price per share the SAFE holder will pay at conversion. Filled in on the header page. Everything else about the SAFE's economics flows from this one number.

A Discount Rate (typically 80% or 85%) can be added, giving the SAFE holder the better of the cap price or a discount to the priced round price. Post-money SAFEs default to cap-only; discount-only or cap-and-discount SAFEs are variations. If the SAFE has both, at conversion the holder gets whichever produces more shares.

The definition of Distribution excludes stock dividends on Common Stock, ordinary-course repurchases at cost, and repurchases under approved stock plans. This matters because Section 4 restricts distributions to Common while the SAFE is outstanding. Ordinary employee-equity repurchases are carved out. Founder secondary sales are not carved out — a founder cannot cash out ahead of SAFE holders without their consent.

Change of Control is defined broadly: a >50% voting-power sale, a merger where the pre-transaction stockholders do not retain majority voting power in the surviving entity, or a sale of all or substantially all assets. The 50% threshold matters — a strategic acquiring 49% is not a Change of Control and does not trigger the SAFE.

Dissolution Event is a voluntary dissolution, general assignment for benefit of creditors, or any liquidation or winding up other than a Liquidity Event. Bankruptcy is not automatically a Dissolution Event; the mechanics depend on whether the estate is being liquidated or reorganized.

When the priced round is above the cap, the SAFE holder receives Safe Preferred Stock — a mirror series with the same rights as the Standard Preferred but a lower per-share liquidation preference (equal to the Safe Price, not the priced-round price). This preserves the priced-round holder's economics on a per-dollar basis and prevents the SAFE holder from getting an inflated liquidation preference for free. It is standard and correct.

The company makes a small set of reps to the investor: it is a duly organized Delaware corporation, it has power to execute the SAFE, the SAFE is a valid and binding obligation, the SAFE does not conflict with other agreements, and it will use commercially reasonable efforts to file any legally required notices.

1. "To its knowledge, the Company has sufficient legal rights to conduct its business." If you have known IP disputes, missing PIIA assignments from prior contractors, or unresolved co-founder equity claims, this rep is not accurate. Fix or disclose before signing. 2. "The Company is not in violation of any judgment, order or decree." Litigation or regulatory orders against the company are disclosure items.

These reps survive signing. A material misrepresentation can support a rescission claim.

The investor reps back that they have full power, that they are acquiring the SAFE for investment (not distribution), and — importantly — that they are an accredited investor. This is what preserves your Regulation D exemption. Do not accept a SAFE from a non-accredited investor without discussing with counsel; the exemption analysis is different and typically more expensive to run.

Amendment requires the written consent of the company and the "Majority in Interest" of SAFE holders. A single SAFE holder cannot unilaterally block a cap-table cleanup. Confirm the Majority in Interest definition matches how you actually track holders.

Transfer restrictions require the company's consent for the investor to transfer the SAFE, with exceptions for affiliates and estate planning. A fund can transfer the SAFE to its GP or to another fund it manages without your consent. An angel can transfer to a family trust. Neither should surprise you at conversion. "Pro Rata Rights." Post-money SAFEs do not automatically include a side letter granting pro rata rights at the next round. Many investors sign a separate MFN or pro rata side letter alongside the SAFE. Track those side letters — they are a real obligation to offer follow-on allocation at Series A and beyond.

Governing law is typically Delaware or the state of incorporation. Jurisdiction is state and federal courts in that state. Do not accept a foreign governing-law provision on a SAFE — the entire template assumes US securities law.

Notices default to the addresses in the header. Update your notices address whenever your registered office changes; SAFE holders send conversion notices, transfer notices, and consent requests here.

1. The Valuation Cap is not the pre-money you are raising at. It is the ceiling for conversion. On a post-money SAFE, the cap is post-money — the SAFE holder gets Purchase Amount divided by cap of the resulting ownership percentage, before the priced round's new money. A $10M post-money cap on a $2M SAFE gives the holder 20% of the company at conversion, before the Series A investors dilute in.

2. Every SAFE stacks. Post-money SAFEs are designed so their ownership percentages add before the priced round. If you sign $500K at a $5M cap, then $1M at a $8M cap, then $2M at a $10M cap, your combined SAFE ownership at conversion is 10% + 12.5% + 20% = 42.5% before any new preferred money and before any option pool refresh. Model this on a spreadsheet every time you sign a new SAFE.

3. The option pool refresh dilutes you, not the SAFE holders. Because Company Capitalization includes the pool refresh, the refresh comes out of the pre-money slice — which is founders plus Common plus employee equity, not SAFE holders. Negotiate the pool size at the priced round with this in mind.

The market default is to sign the standard YC template unedited. There are three narrow edits that are common and defensible:

Fill in every blank. Investor name, Purchase Amount, Effective Date, Valuation Cap, Discount Rate (or "N/A"), state of incorporation, and notice addresses. Missing fields create ambiguity at conversion.

Add a pro rata side letter if the investor is genuinely strategic. Attach it as a separate document, not an edit to the SAFE.

Add an MFN clause if you are signing early SAFEs before your terms have stabilized. This lets the early holder elect the better terms of any subsequent SAFE for a period of time. Sophisticated angels will ask for this.

Everything else — capping SAFE aggregate at a percentage, adding maturity, adding interest, changing conversion denominators, adding board seats — turns the SAFE into a bespoke instrument. If a deal requires those edits, use a convertible note or a priced seed round instead. The SAFE's value is its standardization.

Every seed lawyer sees the same handful of mistakes across hundreds of financings. They are worth naming.

Signing SAFEs without a running cap table model. Each SAFE looks small on its own. Ten of them, at slightly different caps, over eighteen months, are unrecognizable at Series A. Update your fully-diluted post-money model the day each SAFE is signed, and pressure-test it against a realistic Series A raise size and pool refresh.

Confusing the cap with the valuation. A $10M post-money cap is not a $10M pre-money valuation. On a post-money SAFE, the cap is post-money by construction, and the holder's ownership percentage is Purchase Amount divided by the cap, calculated before the priced round dilutes in. Any deck or investor update that describes a SAFE cap as a "valuation" is being loose with language.

Assuming SAFEs behave like notes at a wind-down. SAFEs sit ahead of Common in a Dissolution Event but pro rata against each other. They do not have interest, so the payout is the Purchase Amount only — no coupon accrues while the SAFE is outstanding. Founders who wind down after raising SAFEs and no priced round often find that any residual cash goes to SAFE holders first, with nothing left for the founding team.

Losing track of side letters. Pro rata rights, MFN rights, information rights, and board observer rights are almost always granted in a separate side letter attached to the SAFE. Store side letters with the SAFE itself and add each obligation to your cap table notes. At Series A, the lead will ask for a complete schedule.

Signing SAFEs from the wrong entity. If a fund manages multiple vehicles, the signing entity for a $500K SAFE may not match the wire origin. Ask the investor to confirm the signing entity before you draft, and reconcile the wire the day it arrives. A mismatch is easy to fix at signing and painful to fix at conversion.

Skipping the accreditation confirmation. Most SAFE templates include a rep from the investor that they are accredited. Do not treat this as boilerplate. If you have any doubt, ask for a signed accreditation questionnaire. Your Reg D exemption depends on it.

A SAFE does not live alone. Around each one, you should generate and file a short set of documents so that your Series A diligence process is not a scramble.

The signed SAFE itself, countersigned and dated, stored in your data room under Financing → SAFEs.

The wire confirmation from your bank, matched to the SAFE by Purchase Amount and Effective Date.

Any side letter (pro rata, MFN, information rights), signed the same day and stored alongside.

A board consent authorizing the issuance of the SAFE. For most SAFEs this is a short unanimous written consent; use your standard template.

A Form D filing with the SEC, generally within 15 days of the first sale in an offering, plus any applicable state blue sky notice filings. Your counsel will typically handle these but confirm they are filed — missing Form D filings show up in Series A diligence.

An updated cap table (or SAFE tracker) reflecting the new SAFE, the cap, discount if any, and any side letter obligations.

At Series A, your lead's counsel will ask for every one of these documents for every outstanding SAFE. The teams whose closings run smoothly are the ones who assembled the file the week each SAFE was signed.

Have we updated our SAFE tracker with the Purchase Amount, cap, discount, and Effective Date?

Have we modeled aggregate SAFE ownership at conversion, assuming the current cap and a realistic priced round size?

Have we identified who bears the option pool refresh under a post-money SAFE?

Do any side letters (pro rata, MFN, information rights) accompany this SAFE, and are they tracked?

Have we confirmed the Investor's signing entity matches the wire origin?

A SAFE is quick to sign because the template has been battle-tested a million times. That is the point of the document. But every one you sign is a promise of future equity that will be enforced literally at conversion. The founders who come through their Series A with a cap table they recognize are the ones who read the SAFE the day they signed it, not the day the term sheet arrived.