Ten concrete, expensive mistakes we see in the first 90 days of a startup, and what to do instead before they compound.
Most founder mistakes in the first 90 days don't look like mistakes at the time. They look like reasonable shortcuts. The cost shows up six to eighteen months later, when a VC's lawyer asks for an IP assignment that doesn't exist, when a cofounder dispute surfaces over equity that was never properly documented, or when a customer walks away because your privacy policy was copy-pasted from a competitor and doesn't cover the data you're processing. Below are the ten we see most often, with the version of each that doesn't blow up later.
1. Hiring too fast
The most expensive 90-day mistake. Founders raise a small pre-seed, feel flush, and hire two engineers and a head of growth in month two. Twelve months later, runway is gone, the team built the wrong thing, and you're laying off people whose IP and equity are now an entanglement rather than a contribution.
The fix: keep the founding team at 2 to 4 people through your first 9 months minimum, then hire only against a shipped product with at least a handful of paying or design-partner customers. Contractors are fine; full-time hires before product-market fit are not.
2. Scope-creeping the MVP
The MVP that ships in week 4 is the one that gets feedback. The "MVP" that takes 7 months because you kept adding "must-have" features is the one that gets you stuck. Every feature you add before your first 10 users is a guess about what users want, made by someone who hasn't talked to users.
The fix: define a 4-week MVP scope, then physically remove anything from the spec that isn't required to demonstrate the core value proposition. Ship it. Get 10 users. Then decide what to build next based on what you observed, not what you imagined.
3. Ignoring compliance until a deal stalls
SOC 2, GDPR, HIPAA, PCI, these aren't fundraising checklists, they're customer requirements. The first time you'll feel this is when an enterprise prospect's procurement team sends you a 60-question security questionnaire and you have nothing to fill it out with. The deal slips a quarter. Sometimes it dies.
The fix: if you're selling to anyone bigger than a 50-person company, plan for SOC 2 Type 1 within 9 months. Use Vanta, Drata, or Secureframe, they cost $7,000 to $15,000/year and compress audit prep from 6 months to 6 weeks. Set up basic security hygiene (SSO, password manager, MDM, encrypted backups) from day one regardless.
4. Picking the wrong incorporation state
"I live in California, so I'll incorporate in California." This is a legal answer for a non-VC business and the wrong answer for a VC-track startup. Delaware C-corp is the standard because every VC's documents assume Delaware corporate law, every law firm specializes in Delaware filings, and converting from a California LLC to a Delaware C-corp later costs $3,000 to $8,000 and a month of distraction at exactly the wrong time.
The fix: incorporate as a Delaware C-corp from day one. Pay California (or your home state) the foreign qualification fee, usually $100 to $800/year. That's the cost of doing it right.
5. No founders' agreement (or a vague one)
Two founders, handshake equity split, no vesting, no IP assignment, no decision rights documented. Six months in, one cofounder leaves with 40 percent of the company they no longer work for. This is the single most common cause of pre-seed startup death we see.
The fix: a founders' agreement on day one with: equity split, vesting (4-year with 1-year cliff is standard), IP assignment, decision-making process for major decisions (hiring, fundraising, product direction), and what happens if a founder leaves. Y Combinator's Founder Agreement template or Clerky's templates are fine starting points; spend $500 to $1,500 with a startup lawyer to review the final version.
6. Cap table set up wrong
Common errors: founders issued shares without a stock purchase agreement, no 83(b) filed within 30 days, option pool created in the wrong order relative to the priced round, advisors given common stock instead of options, SAFEs that don't reference the right post-money cap. Every one of these is a $5,000 to $50,000 cleanup at seed, sometimes more.
The fix: use Carta, Pulley, or Capbase from formation. File 83(b) elections by certified mail within 30 days of stock issuance. Read the SAFE before signing it, post-money SAFEs dilute differently than pre-money ones, and stacking 8 SAFEs without modeling dilution is how founders end up at 35 percent ownership before Series A.
7. Sloppy IP assignment
Every contractor, every cofounder, every employee signs a Confidential Information and Invention Assignment Agreement (CIIAA). The version we see most often: founder hires a contractor on Upwork to build the MVP, no IP assignment, contractor disappears, founder discovers during seed diligence that the contractor technically owns 30 percent of the codebase.
The fix: no exceptions on IP assignment. Even your buddy who helped for free needs to sign one before they touch your code or product. Templates from Stripe Atlas, Clerky, or YC are sufficient for early-stage; have a lawyer review for anything unusual.
Avoid all of these by default.
traztech Launch sets up the legal, compliance, IP, and cap table foundation correctly the first time, incorporation, founders' agreements, IP assignments, vesting, the full checklist. Free for accepted pre-seed and seed Delaware C-corps.
See traztech Launch →8. Weak or copied privacy policy
Privacy policies are not decoration. They're a binding contract with your users about what you do with their data. Copying a competitor's policy is a real legal risk: if their policy says "we don't share data with third parties" and you do (Stripe, Sentry, Mixpanel, every SaaS shares data with third parties), you've just put yourself in a worse position than no policy at all.
The fix: use Termly, Iubenda, or Termageddon to generate a custom policy ($10 to $40/month) based on your actual data flows. Update it when you add a new vendor. If you process EU data, you need GDPR-compliant disclosures and a DPA. If you process California data, the same applies under CCPA.
9. No incident response plan
Your first production outage will happen. Your first security event might. The 2024 IBM Cost of a Data Breach Report puts the average breach cost at $4.88 million, most of that cost is response and downtime, not the breach itself. For a startup, the cost is also reputational: if your first incident is also the first time you've thought about incident response, customers find out before you do.
The fix: a one-page incident response plan, written in month one. Who gets paged, who decides whether to disclose, who talks to customers, where you post status updates. Use a template from BetterStack or PagerDuty. You don't need to be sophisticated, you need to have thought about it before the incident, not during.
10. Raising too early (or for the wrong reason)
Raising before you know what you're building means you're raising on a pitch deck instead of on traction, and you'll give up more equity for less money. The valuations in the seed market in 2026 still reward demonstrated user signal, even modest signal, over slide quality. Pre-product, pre-user fundraising is also a major time sink: 3 to 6 months of founder attention pulled out of building.
The fix: raise when you have either a clear product wedge with early user signal, or a track record that lets you raise on the pitch alone. If you're a first-time founder, get to 5 to 20 design-partner customers before you start the seed conversation. Use SAFEs for the first $250K to $1M of friends-and-family or angel money, fast, cheap, and standard.
The pattern across all ten
The mistakes share a structure: a small shortcut early that compounds into an expensive cleanup later. Three months of "we'll set up the IP assignment next week" turns into a $15,000 lawyer bill at seed. A handshake equity split turns into a cofounder lawsuit. The compounding is one-directional, these problems don't get cheaper with time, they get more expensive.
The bottom line
The first 90 days set the operational foundation for everything that follows. The cost of doing each of these correctly is small, usually a few hundred to a few thousand dollars and a day or two of focused work. The cost of cleaning them up at seed or Series A is 10 to 100 times higher and happens at exactly the moment you can't afford the distraction. Pick the boring, complete version over the fast, half-finished version.
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