How to Fill Out a SAFE: A Field-by-Field Walkthrough of the YC Form

Step 1: Download the Right Form

Start at Y Combinator’s documents page, which hosts the current post-money SAFE in three US versions — valuation cap (no discount), discount (no cap), and uncapped MFN — plus an optional pro rata side letter and country variants for Canada, the Cayman Islands, and Singapore. Each version is a complete, self-contained document; you pick one per investor, you do not combine them.

The version choice is the only real decision on the form itself. The cap-only SAFE is the default in most rounds because it fixes ownership the day you sign: purchase amount divided by post-money cap. The discount version defers pricing entirely to your next round, minus the negotiated percentage. The uncapped MFN version has neither mechanism but automatically inherits the terms of any better SAFE you issue later — it shows up most often for the earliest small checks, before anyone can credibly argue a valuation. For how each mechanism plays out at conversion, with worked numbers, see our SAFE conversion math guide.

One warning that saves real money later: make sure you have the post-money SAFE. The original 2013 pre-money SAFE is still widely circulated in old blog posts and document folders, and its conversion math is materially different — other SAFEs are excluded from its denominator, so nobody’s ownership is knowable until the priced round closes. The history and clause-by-clause background of the instrument is covered in our Y Combinator SAFE agreement guide.

Step 2: Fill In the Blanks — Every Field, and the Mistake to Avoid

The post-money SAFE was deliberately built so that the negotiable surface area is tiny. On the cap-only version, this is the complete list of what you fill in:

On the discount version, the valuation-cap blank is replaced by a discount rate — and note the drafting convention: the form states the rate as what the investor pays, so a “20% discount” is written as a discount rate of 80%. Read the definition in the document rather than assuming. On the MFN version there is no economic blank at all beyond the purchase amount.

Step 3: Know What the Standard Sections Do (Without Editing Them)

You will not change any of this text, but you should be able to explain it to an investor across the table. The post-money SAFE is organized into five parts. Section 1 (Events) is the heart of the instrument: it defines what happens at an equity financing (the SAFE converts automatically into preferred stock at the cap price or the round price, whichever favors the investor), at a liquidity event such as an acquisition before conversion (the investor receives the greater of their money back or the as-converted value of their investment), and at a dissolution (the investor is paid back, if funds remain, before common stockholders receive anything). It also sets the SAFE’s payout priority relative to other claims.

Section 2 (Definitions) is where the conversion math lives — Company Capitalization, Safe Price, and their siblings determine exactly how many shares the purchase amount buys. Section 3 (Company Representations) and Section 4 (Investor Representations) are short mutual promises: the company confirms it is duly formed and authorized to issue the SAFE, and the investor confirms they are acquiring it for investment purposes and are financially sophisticated — language that supports the securities exemption discussed below. Section 5 (Miscellaneous) covers mechanics: amendments require written consent of both parties, notices go to the addresses in the signature blocks, the SAFE is not transferable except in limited cases, and — worth saying out loud — the SAFE holder is not a stockholder and has no voting or dividend rights until conversion.

If an investor wants something the standard text does not give them — pro rata participation in the round the SAFE converts into, information rights, an MFN promise — the clean answer is a side letter that sits alongside an unmodified SAFE. That keeps the SAFE recognizable and puts every deviation in one visible document. We cover what founders should and shouldn’t grant in our SAFE side letter guide.

Step 4: The Approvals and Filings Around the Signature

Filling in the blanks is the easy half. A SAFE is a security, and issuing securities carries process obligations that the form itself cannot satisfy:

None of this is exotic — it is a few hours of counsel time per round — but skipping it converts a clean fundraise into a diligence problem. When your SAFEs eventually convert, they do so inside a priced round papered on the NVCA model legal documents; our Series A closing documents guide walks through that suite.

The 60-Second Check Before Anyone Signs

Run this list against the filled-in document. It catches nearly every error we see founders make:

• Is this the current post-money SAFE from YC’s documents page — not a pre-2018 pre-money form?
• Does the company name match the certificate of incorporation exactly, including the entity suffix?
• Is the investor name the entity that will actually send the wire?
• Do the purchase amount and cap match the deal you agreed — and have you re-run total dilution across all outstanding SAFEs at these numbers?
• Is there a board consent authorizing this issuance?
• Is the investor accredited, and is your Form D / blue-sky process in motion?
• Are any negotiated extras in a side letter rather than edits to the SAFE text?

If you want to pressure-test the economics before committing to a cap, our free SAFE calculator and dilution calculator model conversion across round sizes — and if you are still deciding between SAFEs and pricing the round now, start with our SAFE vs priced round comparison.