How to Write a SAFE That Both Sides Understand

The valuation cap is the highest valuation at which a SAFE converts. If your next priced round values the company above the cap, the SAFE converts at the cap, rewarding the early investor the YC SAFE page. Because the post-money cap includes the SAFE investment itself, the ownership you sell is immediately visible to both sides.

The clean way to set it is backward from the raise, not forward from a valuation you like. YC suggests starting from how much you are targeting and how much ownership you are willing to sell, then solving for the cap: a $1M raise selling 15% implies a post-money cap of about $6.7M the YC SAFE page. Raise less on the same cap and you sell less; raise on multiple caps and the ownership adds up.

Here is a worked stack. Founders start at 100% and sign three post-money SAFEs before any priced round:

After those three SAFEs, the founders hold about 69.17% before the priced round and before any option pool expansion, which matches the worked example published by Avisen Legal Avisen Legal. The priced round then dilutes everyone again. This is the decision rule most founders miss: the cap on the last SAFE you sign does not just price that investor, it sets the floor under how much of the company you have left when the Series A lead arrives.

The other failure mode is a cap set far below your expected next-round valuation. If you raise a SAFE at a $5M cap and later price at $10M, the SAFE investor converts at roughly half the price the new investors pay, an effective discount close to 50% the TKNTyson Law guide. That is not a disaster in itself if the money buys real progress, but it should be deliberate. Founders who cap low to close a round often find the Series A lead asking why so much of the company is already gone.

Negotiation points on the cap:

• Agree the cap as a post-money number and write it that way, never as an ambiguous "valuation."
• Model the full stack at your expected Series A price before you sign the third SAFE, not after.
• If an investor will not move on price, move on amount: a smaller check on the same cap sells less ownership.
• Ask whether the cap should include a discount as well, since a SAFE with both gives the investor whichever produces more shares CRV's SAFE guide.

A discount gives the SAFE holder a lower price per share than the new money in your priced round. On a 20% discount, an investor pays 80% of what the new investors pay, which works out to 25% more shares for the same money CRV's SAFE guide. If the next round prices at $5.00 per share, the SAFE investor converts at $4.00 the TKNTyson Law guide.

Put numbers to it. An investor puts in $100,000 with no cap and a 20% discount, and your Series A prices at $5.00 per share. The investor gets 25,000 shares ($100,000 divided by $4.00) instead of 20,000. At a post-Series-A price of $5.00, that extra 5,000 shares is $25,000 of value, paid for with a 20% concession on price.

Two mechanics decide how much the discount costs you:

• Cap plus discount. When a SAFE carries both, the investor converts at the lower of the two prices. On a fast-growing company the cap usually binds, so the discount is insurance that costs little. On a flat round the discount binds.
• Discount only. CRV describes discount-only SAFEs as less common and best suited to situations where setting a valuation still feels premature CRV's SAFE guide. TKNTyson Law notes that many investors refuse a SAFE without a cap unless the startup has unusual leverage the TKNTyson Law guide.

The insight a first search will not give you: a discount is a bet about the shape of your next round, and a cap is a bet about its size. If you expect the valuation to rise sharply, the cap is worth fighting harder on than the discount. If you expect a modest step up, the discount is the term that actually binds, so cap the discount instead (common practice sits in the 10% to 20% range per TKNTyson Law) and leave the cap loose.

Worth knowing from market data: about 72% of SAFEs issued in 2025 used a valuation cap with no discount, making cap-only the dominant structure by a wide margin CRV's SAFE guide. If an investor insists on both, that is a negotiation position, not a market norm.

Negotiation points on the discount:

• Ask whether the cap or the discount binds at your expected round size, and put the answer in writing in your model.
• Cap the discount percentage rather than accepting an open-ended "market discount."
• Refuse a discount that runs past the first priced round; a discount that survives multiple rounds compounds against you.

Pro rata rights live outside the SAFE, in an optional standardized side letter, and give the investor the right (not the obligation) to buy shares in the next priced round to maintain their percentage the YC SAFE page. The side letter is a short document that points back to the SAFE and defines the pro rata share as the shares issued on conversion divided by company capitalization just before the financing the line-by-line side letter explainer.

The mechanical problem is allocation. A Series A lead typically wants to own a meaningful percentage, and your check size for the round is finite. If several small SAFE holders each hold pro rata, they can consume allocation the lead expected to fill, which complicates closing. CRV calls this out directly and recommends limiting pro rata to the largest check writers and restricting it to the next round only CRV's SAFE guide.

A worked example makes the squeeze concrete. Say your Series A is $6M and the lead wants 18% post-money, with 30.83% of the company already sold to SAFE holders from the table above. If all three SAFE holders exercise full pro rata, they jointly put in roughly $1.85M of the round (30.83% of the post-money pie, apportioned against the new money). The lead now has $4.15M to deploy against an 18% target and either asks for a lower price, asks you to shrink the round, or walks. You have not lost the round, but you have lost leverage at exactly the moment you need it.

The side letter also terminates on defined events, typically the initial closing of the equity financing, a liquidity event or a dissolution event the line-by-line side letter explainer. Read that termination clause closely: a pro rata that survives into a second round is a different, much more expensive right.

Negotiation points on pro rata:

• Give it only to investors above a check-size threshold, and write the threshold down.
• Restrict it to the next priced round, with automatic termination at that closing.
• Require the investor to exercise within a fixed window (commonly a short notice period) before the allocation is released.
• Exclude it from MFN SAFEs unless the investor is paying for it with a larger check.

An MFN SAFE has no cap and no discount. Instead, it automatically takes the cap or discount of any SAFE you issue later, so the investor can put money in now without deciding those terms the YC SAFE page. It is meant for a short bridge from trusted investors when a priced round is near, and it turns into a trap when the bridge gets long.

The trap has a specific shape: every concession you make to a later SAFE is automatically extended to every MFN holder. CRV states the tradeoff plainly: one concession can affect all MFN holders, which reduces your flexibility in later SAFE negotiations CRV's SAFE guide.

Run the numbers. You raise $250,000 on an MFN SAFE early. Eight months later you raise $750,000 at a $6,000,000 post-money cap. The MFN investor now adopts that $6M cap and converts at $250,000 divided by $6,000,000, about 4.17%. Fine. But if a later angel negotiates a $4,000,000 cap, the MFN investor adopts that too, converting at about 6.25%. You have effectively given the earliest investor the best price of the whole round, retroactively.

Negotiation points on MFN:

• Put a floor or a defined reference set on the MFN: it adopts terms from SAFEs issued within a stated window, not forever.
• Write in that the MFN does not pick up pro rata rights or side letters, only the economic terms.
• Set an expiry: if no priced round closes by a certain date or the MFN SAFE's amount is small, the clause lapses.
• Never issue an MFN alongside a round where you expect to negotiate several different caps, because the best cap propagates to every MFN holder.

The document is short enough to review in one sitting if you know what to look for. Use this as the pre-signature pass, and have a lawyer confirm anything you are unsure about; standardized does not mean legal advice is optional the TKNTyson Law guide.

The arithmetic you must be able to run yourself is simple enough to keep in a spreadsheet:

ownership_sold = investment / post_money_cap
founder_remaining_before_round = 1 - sum(ownership_sold for each SAFE)
post_round_founder = founder_remaining_before_round * (1 - new_money_pct - pool_pct)

If that last line starts to look thin, you are not negotiating a SAFE anymore, you are negotiating whether you will still be a meaningful owner at Series A. That is the moment to stop signing and start modeling.

Carta's guidance is to decide, before you raise, how much equity you plan to give up, how much you want the next priced round to be and what milestones the SAFE money buys Carta's SAFE explainer. Those three answers drive every clause above.

Post-money SAFEs are the market default, and most investors will expect one unless you negotiate something else Avisen Legal. The practical implication is that you should build the cap table forward, SAFE by SAFE, at a fully diluted post-conversion basis rather than eyeballing it.

The reason is structural. Under the post-money form, subsequent SAFEs dilute founders, not earlier SAFE holders Avisen Legal. Stacking three or four post-money SAFEs without a model is one of the more common ways founders reach a Series A with less ownership than they expected Avisen Legal. That is not a hypothetical: the 30.83% figure in the table above is the arithmetic of three ordinary SAFEs, not an extreme case.

Two habits keep this under control. First, keep the cap table in one place with each SAFE's amount, cap and implied percentage, and update it the day you sign rather than the day you close. Second, review the SAFE stack monthly in the boring way: ask what each clause would do if the next round priced at, above and below the last cap. The clause that hurts you is usually the one you did not model, and it is almost always pro rata or MFN.

When you are raising the priced round itself, the work becomes a pipeline problem: a target list, staged meetings and a weekly review, run like a sales process rather than a series of one-off conversations startupfundraising.com. The SAFE stack is the input to that process, and the cleaner the stack, the simpler the diligence conversation.

If you would rather not model the cap table alone, a short working session with someone who has seen hundreds of SAFE stacks can save an expensive mistake; Quanta's consulting team offers a free 30-minute discovery call to look at your goals and give a tailored recommendation Quanta Consulting.