Source Digest — Summers & Sarin, "A 'Wealth Tax' Presents a Revenue Estimation Puzzle"

Status (April 2026): Complete standard digest. The most influential center-left challenge to Saez-Zucman's revenue estimate. Companion to Sarin & Summers's broader work on tax-gap enforcement (NBER, 2019) which makes the practical case for enforcement-driven revenue expansion without a wealth tax.

Source identification

Thematic cluster 1: the revenue estimation puzzle

Core claims

• Historical evidence on avoidance and evasion in existing U.S. tax instruments suggests much higher baseline leakage than Saez & Zucman assume.
• The estate tax — analogous in its targeting of high-net-worth households — has effective realization rates closer to 50% than 85% once avoidance, undervaluation, and planning are accounted for.
• Applying estate-tax-like avoidance assumptions to a wealth tax reduces the Saez-Zucman revenue estimate by 50–75%.
• Specifically, Summers and Sarin estimate a Warren-style wealth tax would raise closer to $25B–$35B per year rather than Saez-Zucman's ~$210B per year in steady state.
• Therefore, rhetoric promising very large new spending from the revenue is not credible without enforcement capacity investments that do not currently exist.

Representative excerpt

"We do not believe, based on the evidence of existing tax avoidance and evasion, that wealth taxes can realistically raise the revenues their sponsors project. The estate tax, a close analog, collects a fraction of the revenue that its statutory base would imply. A wealth tax is likely to face similar or greater erosion."

Thematic cluster 2: the enforcement-first alternative

Core claims

• A far larger revenue pool is available through existing-instrument enforcement than through new wealth taxation.
• Sarin & Summers's companion NBER paper estimates that restoring IRS audit capacity, expanding third-party reporting, and improving compliance technology could raise on the order of $1 trillion over 10 years — a figure comparable to the aggressive Saez-Zucman wealth-tax estimate, without the administrative novelty.
• This is a politically and administratively more tractable path to raising meaningful revenue from high-income households while maintaining legal continuity.

Research context

Interpretive notes

• Summers and Sarin are not against progressive taxation. Both have publicly endorsed higher taxes on capital gains, closing step-up basis, and expanded IRS funding. Their dispute with Saez-Zucman is about method and feasibility, not values.
• The exchange between Saez-Zucman and Summers-Sarin represents the most productive methodological debate on U.S. wealth-tax feasibility. The project should include both sides and their direct exchange, not one in isolation.
• The enforcement-first strategy offers Project 2028 a concrete policy variable: even within the existing legal framework, large revenue gains are available through enforcement and reporting upgrades. That is a bounded-governance-compatible lever — strengthening an existing instrument rather than creating a new one.

Project 2028 mapping

• Exchange: Government Overreach, Ownership as Transition, and the Ratchet Problem. The Summers-Sarin line is a valuable middle option: a way to raise meaningful revenue from high-income households without the administrative novelty (or the precedent-concern Friedberg raises) of wealth taxation.
• Problem Map: Domain 10 (Wealth and power concentration), Domain 4 (Institutional capacity). Summers and Sarin name a §4 binding constraint on §10 remediation: the administrative-capacity gap that determines whether wealth-tax proposals deliver the revenue their advocates project.
• Principles: Direct fit with Principle 4 (accountable, legible, reversible power) — the tax-gap closure strategy is about making existing obligations legible and enforceable.
• Round 2 use: Present Summers-Sarin and Saez-Zucman as a two-hypothesis test. The project does not need to resolve which is right; it can note that the enforcement path is available even under conservative revenue estimates.

Cross-references