Stacked SAFEs: Dos and Don'ts for Tracking What You've Actually Sold

Many founders raise a seed in pieces: a few SAFEs at one valuation cap, then more at a higher cap. Each one looks small. Together they can sell more of the company than the headline cap suggests. This guide explains how SAFEs stack under Y Combinator's standard post-money SAFE (US forms), and what to track before your first priced round.

Scope: this follows the published YC post-money SAFE forms and User Guide. Older pre-money SAFEs, edited SAFEs, convertible notes and non-YC forms can work differently. Your signed documents control.

Do: Treat each SAFE's ownership as amount ÷ cap

With a post-money valuation cap, the ownership a SAFE buys is roughly purchase amount ÷ post-money valuation cap. YC's own example: $500k at a $6.7M post-money cap is about 7.5%. To see your total, add up amount ÷ cap for every SAFE.

"Post-money" here means after all the SAFE money, but before the priced round's new money and before any option pool increase agreed in that round. So SAFEs don't dilute each other, but they are all diluted later by the priced round.

Don't: Quote your latest cap as "the" valuation

If you raised at two caps, neither cap tells the whole story. A simple check is the blended cap: total SAFE money ÷ total percentage sold. In the example below, $1.0M bought 17.5%, a blended cap of about $5.71M, even though the latest SAFE had an $8M cap.

Synthetic worked example: two SAFEs, then a Series A

Synthetic example: made-up company and numbers, chosen to keep the math round. Not market data or a recommendation. Share counts rounded to whole shares.

Before any SAFEs: 9,000,000 fully diluted shares. Founders hold 8,000,000 common shares. The option plan has 600,000 granted options, 150,000 promised but not yet granted, and 250,000 unissued.

SAFEs raised:

• SAFE 1: $400,000 at a $4,000,000 post-money cap = 10% sold.
• SAFE 2: $600,000 at an $8,000,000 post-money cap = 7.5% sold.
• Total: $1,000,000 for 17.5%. Blended cap: $1,000,000 ÷ 17.5% ≈ $5,714,286.

Conversion at the Series A. The post-money SAFE converts using a denominator it calls Company Capitalization: existing shares, granted and promised options, the unissued pool, and all converting SAFEs, but not the Series A pool increase. Because the SAFEs must end up at 17.5% of that total:

• Company Capitalization = 9,000,000 ÷ (1 − 17.5%) ≈ 10,909,091 shares.
• SAFE 1 converts into about 1,090,909 shares (10%), at about $0.3667 per share ($4,000,000 ÷ 10,909,091).
• SAFE 2 converts into about 818,182 shares (7.5%), at about $0.7333 per share.
• Founders, just after conversion: 8,000,000 ÷ 10,909,091 ≈ 73.33%.

The Series A (also synthetic): $3,000,000 of new money at a $12,000,000 pre-money valuation. The term sheet requires 1,090,909 new pool shares, counted in the pre-money. Price per share, using the same convention as YC's worked example (term sheets vary) = $12,000,000 ÷ (10,909,091 + 1,090,909) = $1.00. New investors get 3,000,000 shares, for 15,000,000 fully diluted shares in total.

After the Series A (fully diluted):

• Founders: 8,000,000 ≈ 53.33%
• SAFE 1 holders: 1,090,909 ≈ 7.27%
• SAFE 2 holders: 818,182 ≈ 5.45%
• Series A investors: 3,000,000 = 20.00%
• Granted and promised options: 750,000 = 5.00%
• Unissued pool after the increase: 1,340,909 ≈ 8.94%

The SAFEs' combined 17.5% becomes about 12.73% after the Series A, because they share the dilution from new money and the new pool. The founders go from 88.89% before the SAFEs (8,000,000 ÷ 9,000,000) to about 53.33%.

Do: Check whether the cap actually applies

Under the cap form, a SAFE converts into whichever gives the holder more shares: the cap-based price, or the price new investors pay. In the example, the $1.00 Series A price is above both SAFE prices, so the caps apply. If a priced round came in below about $0.7333 per share, SAFE 2 would convert at the round price instead and receive more than the 7.5% implied by its cap. YC's guide warns that when the round's valuation is below or close to the cap, SAFEs can convert into more than the estimated ownership. Model a "flat" or "down" priced-round case, not just the hoped-for one.

Don't: Forget the other SAFE flavors in the stack

• Discount SAFEs: in YC's discount form, the "Discount Rate" is written as 100 minus the discount. A 20% discount means an 80% Discount Rate: at a $1.00 round price, the holder converts at $0.80. Synthetic illustration, separate from the example above: $100,000 ÷ $0.80 = 125,000 shares. You won't know the exact percentage until the round is priced.
• Uncapped MFN SAFEs: these take the best cap or discount of later SAFEs. YC says the relevant date is the later of signing and the investor's wire, so the order and timing of your closes matters.
• Pro rata side letters: a pro rata right lets a SAFE holder buy into the round where the SAFE converts. That can shrink the space for new investors or add dilution. List every side letter with the SAFE it belongs to.
• Convertible notes and other converting securities also count in the post-money SAFE's denominator. Model each from its signed terms.

Do: Keep the paperwork and compliance basics straight

These are common US flags to raise with counsel, not a complete list:

• Board approval. YC's SAFE FAQ says the board must approve issuing SAFEs.
• Investor eligibility. YC says SAFE investors should be accredited. The SEC's accredited investor page lists the criteria, such as net worth over $1 million excluding a primary residence, or income over $200,000 individually ($300,000 with a spouse or partner) in each of the prior two years with the same expected this year. Professional and entity tests also exist.
• Form D timing. SAFEs are securities. If you rely on Rule 504 or 506 of Regulation D, the SEC says a Form D notice is due within 15 days after the first sale, which it defines as the date the first investor is irrevocably contractually committed to invest. Its Rule 506(b) page notes that states can still require notice filings and fees.
• No public pitching under 506(b). The SEC says Rule 506(b) offerings can't use general solicitation or advertising. Talk to counsel before posting about a raise in progress.
• Unmodified forms, separate side letters. YC recommends keeping the SAFE unmodified and putting extra rights in a side letter.

Tax and accounting treatment of SAFEs varies. Ask your accountant or tax adviser.

Pre-priced-round SAFE checklist

1. List every SAFE: holder, purchase amount, cap or discount or MFN, date signed, date funded, and any side letter.
2. For capped SAFEs, add up amount ÷ cap and compute your blended cap.
3. Split your option plan into granted, promised and unissued options. These count in the SAFEs' denominator. The Series A pool increase does not.
4. Run at least two priced-round scenarios: one well above your caps and one at or below your highest cap.
5. Note which holders have pro rata rights and roughly how much of the round they could take.
6. Confirm board approvals, investor eligibility records and any Form D or state filings with counsel.
7. Rebuild the pro forma cap table from signed documents, not from memory or a spreadsheet summary.

You can try sample priced-round scenarios in the RaisePlan priced-round dilution demo, and read the priced-round dilution guide for how the pool top-up works.

Sources (accessed Nov 9, 2026)

• Y Combinator, The SAFE: documents, FAQ and forms
• Y Combinator, Post-Money SAFE User Guide (PDF; latest change log entry: Version 1.2, February 2023)
• Y Combinator, SAFE conversion calculator
• SEC, Filing a Form D notice (last reviewed Mar 17, 2026)
• SEC, Private placements: Rule 506(b) (last reviewed Sept 21, 2026)
• SEC, Accredited investors (last reviewed Apr 24, 2026)