# The 10% Seed Capital Rule & Estate Tax Debt vs. Equity Substantive Case Law

**Core Requirement**: To ensure an installment sale to an Intentionally Defective Grantor Trust (IDGT / IDIT) is respected as a bona fide sale for debt rather than a retained equity or income interest under IRC §§ 2036, 2038, 2701, or 2702, the trust must possess significant equity—traditionally **at least 10% of the value of the assets to be sold**.

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### Judicial & Legal Foundations

1. **Debt vs. Equity Characterization (*Fidelity-Philadelphia Trust Co. v. Smith*)**:
   In *Fidelity-Philadelphia Trust Co. v. Smith*, 356 U.S. 274 (1958) (the judicial reasoning of which is applied by analogy in the IDGT context), the Supreme Court established that for an obligation to be respected as bona fide debt rather than a retained income interest under IRC § 2036:
   - The obligation must be a personal liability of the obligor (or backed by independent trust equity).
   - Payments must not be tied directly to, or contingent upon, the actual income generated by the transferred assets.

2. **The 10% Seed Equity Benchmark**:
   While the Internal Revenue Code contains no statutory 10% rule for IDGT sales, tax practitioners and IRS auditors rely on informal benchmarks derived from private letter rulings (e.g., PLR 9535026) and analogies to IRC § 2701(a)(4) (minimum valuation of junior equity).
   - **Independent Seeding**: Ideally, the seed equity should consist of cash or liquid assets **separate from the specific asset being sold** to the IDGT.
   - **Timing**: The seed contribution should occur prior to the sale transaction to establish independent economic viability.

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### Key IRS Challenge Cases & Audit Lessons

1. ** *Estate of Woelbing v. Commissioner* (T.C. Docket No. 30261-13)**:
   - **IRS Position**: The IRS challenged a $59M IDGT installment sale of closely held stock, asserting that because the trust lacked sufficient independent equity to support the note without relying on dividends from the sold stock, the transaction was a transfer with a retained income interest under IRC § 2036 and § 2038, or a retained annuity under IRC § 2702 valued at $0.
   - **Resolution**: Settled prior to trial with zero § 2036 inclusion, reinforcing the critical necessity of robust independent seed equity and strict note administration.

2. ** *Estate of Davidson v. Commissioner* (T.C. Docket No. 13748-13)**:
   - **IRS Position**: Involving the sale of $900M+ of private business stock for self-canceling installment notes (SCINs), the IRS asserted § 2036, § 2038, and gift tax deficiencies, alleging the notes lacked bona fide debt characteristics.
   - **Audit Takeaway**: Notes must bear commercial interest rates (AFR), have fixed repayment schedules, be executed by solvent trusts with real equity, and be strictly enforced by the trustee.

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### Administrative Best Practices for IDGT Installment Sales

1. **Seed Funding Ratio**: Fund the IDGT with cash or unencumbered liquid assets equal to at least 10% of the intended purchase price prior to executing the note.
2. **Guarantees**: If seed equity is under 10%, obtain personal guarantees from trust beneficiaries with independent net worth (charging a reasonable guarantee fee of 1%–2%).
3. **Strict Note Administration**: Make all interest and principal payments strictly on schedule via wire transfer or documented asset assignments.