This recipe produces a structured Co-Founder Compatibility Report that scores candidate co-founders across six critical dimensions, generates an evidence-based equity split recommendation, and outputs a co-founder agreement checklist. The deliverable replaces gut-feeling co-founder selection with a scored, documented evaluation that reduces the single largest cause of startup failure — co-founder conflict.
The evaluation covers 5 steps: (1) Skills Complementarity Assessment using a 12-skill matrix to identify coverage gaps and overlap, (2) Commitment and Alignment Assessment through structured conversations on 10 critical topics including full-time dates, funding approach, and exit expectations, (3) Working Trial Period of 2-6 weeks on a real project with structured evaluation checkpoints, (4) Equity Split Negotiation using YC's recommended equal-or-near-equal approach with explicit adjustment factors, and (5) Compiled Compatibility Report with agreement checklist for legal review.
The scoring uses six weighted dimensions: Skills Complementarity (0.25), Commitment Alignment (0.25), Trial Period Performance (0.25), Equity Agreement (0.10), Reference Checks (0.10), Personal Compatibility (0.05).
| Quality Metric | Minimum | Good | Excellent |
|---|---|---|---|
| Trial period length | 2 weeks | 4 weeks | 6+ weeks |
| Reference checks per candidate | 1 | 2 | 3+ professional |
| Alignment topics discussed | 5/10 | 8/10 | 10/10 documented |
| Independent equity proposals | Within 15% | Within 10% | Within 5% |
| Legal review | Template only | Attorney-reviewed | Custom-drafted |
Wrong: Splitting equity based on who had the idea. Ideas are worth almost nothing — execution is everything. [src1] [src5]
Correct: YC recommends equal or near-equal splits. The work is ahead of you, not behind. Adjust by 5-10% maximum for genuine asymmetries.
Wrong: Handshake deal with no vesting. Without vesting, a co-founder who leaves after 3 months retains their full equity stake. [src2]
Correct: 4-year vesting, 1-year cliff, no exceptions. This protects both founders equally.