---
title: "What Is ECI?"
term: "ECI"
description: "ECI (effectively connected income) is U.S.-source income tied to a trade or business in the United States—taxable to foreign investors and relevant in cross-border VC deals."
date: 2026-07-25T00:00:00.000Z
updated: 2026-07-25T00:00:00.000Z
topics: ["venture-capital"]
source: https://venturecapitaltracker.com/glossary/eci
---

# What Is ECI?

> ECI (effectively connected income) is U.S.-source income tied to a trade or business in the United States—taxable to foreign investors and relevant in cross-border VC deals.

**ECI** (effectively connected income) is U.S. tax terminology for income that foreign taxpayers earn from a U.S. trade or business—subject to U.S. taxation at net rates, not just passive withholding.

## How it works

Foreign investors generally invest in U.S. startups through funds or holding companies to manage U.S. tax exposure. When a fund realizes gain from operating companies (not purely portfolio debt or certain passive structures), the IRS may classify some income as **ECI**.

ECI requires foreign investors to file U.S. tax returns and pay tax on net income connected to U.S. operations—different from fixed-percentage withholding on passive FDAP income.

Fund lawyers use **blocker corporations**, **offshore feeders**, and treaty analysis to reduce ECI and FIRPTA complications for non-U.S. LPs. Terms vary by investor domicile (pension, sovereign wealth, corporate).

Founders rarely calculate ECI daily, but cross-border cap tables—European angels, Asian strategics, offshore funds—raise questions at exit when buyers withhold or demand tax representations.

## Why it matters

- **Founders:** Large foreign ownership may influence deal structure at IPO or M&A. Buyer counsel asks tax reps; surprises delay closing.
- **Investors:** Non-U.S. LPs diligence fund documents for ECI policy and gross-up clauses. Unexpected ECI hurts net returns.
- **Fund counsel:** Side letters and entity choice are driven partly by ECI and UBTI (for tax-exempt U.S. investors).

## Common mistake

Assuming offshore incorporation alone eliminates U.S. tax on U.S. operating company gains. Operating business income can still flow through as ECI depending on structure and activity level.

## Related ideas

- FIRPTA — U.S. real property holding tax on foreign sellers
- Blocker corp — tax block between foreign LP and U.S. assets
- [ERISA](/glossary/erisa) — separate U.S. regulatory concern for pension capital
- Withholding tax — passive vs ECI treatment differs

## FAQ

### What is ECI in simple terms?

Income foreign persons earn that the IRS treats as connected to doing business in the U.S.—not passive portfolio income. It can trigger U.S. tax filing and withholding for offshore investors.

### Why does ECI matter?

Foreign LPs in U.S. VC funds may owe U.S. tax on ECI from active business gains. Fund structures and blocker corporations exist partly to manage ECI exposure for non-U.S. allocators.


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Source: https://venturecapitaltracker.com/glossary/eci