There shouldn't be any tax consequences for the founders if you've made 83b elections--the election meant you paid tax already on the full value of the stock at the time of the election (presumably zero) even though it was subject to future forfeiture. If you sell newly-issued stock there should be no tax impact. If you sell your own common stock, you'd pay tax on the gain, but I doubt that is what you mean here.

Of course, you should not take the free advice dispensed on Clarity and consult your own tax preparer--this is not tax advice.

My answer will:
1️⃣ Give you a simple summary up front
2️⃣ Explain what actually happens when investors take common stock
3️⃣ Show why many founders misunderstand this issue — and what was missed in the previous answer

✅ TL;DR (Too Long; Didn’t Read)
No, investors taking common stock instead of preferred does not trigger tax for founders if they’ve already filed an 83(b) election and aren't selling their own shares.
But if the investors' purchase sets a new fair market value (FMV) for common stock, it may affect:
Future equity grants
409A valuations
And taxes on future common stock issuances, including to late-joining co-founders or employees

🧠 Full Answer
Here’s the real-world breakdown:

📁 1. Your 83(b) Election Locks In Your Tax Basis
You said:
"The founders all have common stock which was valued nominally at time of incorporation. An 83(b) election was filed."
✅ That means you already paid tax (usually zero) on the full value of your founder shares.
✅ Even if the stock later becomes valuable, the IRS treats your cost basis as fixed.
✅ You won't be taxed again unless you sell.

📈 2. What Changes When Investors Buy Common Stock at a Higher Price?
Here’s where it gets tricky:
When seed investors buy common stock (instead of preferred):
They’re setting a real, priced market transaction
That can reset the fair market value (FMV) of your common shares in the eyes of the IRS
Even though you’re not selling, that new FMV can trigger:
Higher 409A valuations
Higher strike prices for stock options
More tax burden on future hires or co-founders who receive common shares

But not on you — unless you’re:
Selling your own shares
Issuing yourself more common stock

💸 3. Why Do Some Say Founders Could Owe Tax?
Because if:
The company sells new common stock to investors at $1/share, and
You issue new common shares to someone else at $0.01/share, then

The IRS may say that’s a below-FMV transfer — and the recipient owes ordinary income tax on the difference
But if no new stock is issued to founders — and your 83(b) is filed — you’re safe.

🔍 What Was Missed or Oversimplified in the Previous Answer
❌ “There shouldn't be any tax consequences for founders if you filed an 83(b)”
→ Mostly correct — but it ignores FMV reset risk and downstream consequences for future equity awards.

❌ No mention of 409A implications
→ That’s the biggest real-world effect: your option pricing and equity compensation become more expensive.

❌ No guidance for future grants or second hires
→ Many startups forget that granting new common stock after a priced round could trigger ordinary income tax if not handled carefully.

✅ The 83(b) point is solid — and that protects you, as long as you’re not receiving or selling stock after the priced round.

🧭 Final Word
✅ If you filed 83(b) at nominal value, you won’t owe more taxes as a founder — even if investors buy common stock later.
✅ But their purchase may affect your company’s valuation, option pricing, and ability to grant low-cost equity going forward.
✅ Talk to your CPA or startup counsel before issuing any more common shares after that round.

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Still unsure about 409A timing or structuring your seed round? I’m happy to schedule a call and go through it step-by-step.