Objection: Land value can't be assessed accurately

The Objection

A land value tax requires assessing land separately from the buildings on it. Critics argue this is impractical: in dense cities, land rarely sells unimproved, so there are few "pure land" sales to benchmark against. Inaccurate or arbitrary assessments would make the tax unfair and legally vulnerable.

The Response, with Evidence

The objection is serious but is generally treated as a solvable engineering problem, not a fundamental barrier.

1. It is already done at scale. Estonia (pure land tax since 1993), Denmark's grundskyld, and several Australian states assess land values separately as routine practice. Most US assessments already publish a land/improvement split. The US Federal Housing Finance Agency has since turned millions of appraisals into land prices and land shares for every county, ZIP code and census tract — a demonstration that land can be valued separately from structures at national scale.

2. Land is easier to assess than buildings, not harder. In Does Georgism Work? Part 3 (2022), Lars Doucet makes the key counter-intuitive point: land value is spatially smooth — neighbouring parcels have similar land values — whereas building value varies house-by-house. That smoothness means location-based methods (comparable vacant-lot sales, teardown sales, and the "residual" of sale price minus depreciated structure cost) can estimate land value with accuracy comparable to or better than whole-property assessment. Career assessor Ted Gwartney's practitioner account of estimating land values — the expert Doucet consulted — describes exactly these location-based methods as routine professional practice.

3. Modern methods exist — including where data is thin. Computer-assisted mass appraisal (CAMA), hedonic regression, and cooperative-game approaches such as the Shapley-value land/building separation (Humanities and Social Sciences Communications, 2020) formalise the split. And the "it only works with rich sales data" version of the objection is answered directly: Bencure et al. (2019) built an expert-weighted (AHP) land-valuation model for sub-urban Baybay City, Philippines, that explained ~67% of land-value variability and outperformed ordinary multiple regression — a developing-country case with sparse market data.

3a. Even dense cities generate pure-land sales. The premise that unimproved land "rarely sells" in built-up cores is overstated: Barr, Smith & Kulkarni constructed a 64-year (1950–2014) land-value index for Manhattan — one of the densest markets on earth — using vacant-land transactions alone.

4. Errors are bounded and contestable. Because land is immobile and visible, gross mis-assessment is easy to challenge; assessment quality improves with investment (the focus of the Center for Land Economics, co-founded by Doucet). Independent evidence bears this out: hedonic decomposition of over a million home sales separates land from structure at scale (Kuminoff & Pope), and Australian mass-appraisal appeal rates run well below the internationally accepted 2% benchmark (Hefferan & Boyd) — revealed taxpayer acceptance that value-based land assessment is treated as reliable.

A documented real-world failure mode supports the objection's premise while locating it precisely: a 2005 New South Wales Ombudsman investigation found state Valuer-General assessments relied on outdated sales data and were biased conservative by litigation-avoidance incentives — understating land values so systematically that Australia's national statisticians abandoned VG data for a residual method (see Recording Land in the National Balance Sheet). The lesson cuts both ways: assessment institutions can fail, and the failure documented was under-valuation by a cautious bureaucracy, not the arbitrary over-taxation the strong objection fears.

Net Assessment

Assessment difficulty raises the cost and care of implementing LVT well; it does not undermine the case. The objection is best read as an implementation agenda, not a refutation.

See Also

• "LVT Enables Corrupt Assessors and Will Be Gamed" — the companion political-economy objection: not whether land value can be measured, but whether the measurer can be trusted
• Domesday Book (1086) — an 11th-century nationwide land-value survey showing large-scale land assessment is not a modern invention requiring modern tools.
• Johannesburg Site Value Rating — a documented site-value-only tax base run at municipal scale from 1918/1919, cited by Fred Harrison as evidence against the claim that isolating land value is impossible
• Ted Gwartney — career assessor whose British Columbia and Connecticut work is cited as practical counter-evidence to this objection
• Kuminoff & Pope — tract-level hedonic land/structure separation at million-transaction scale
• Kolbe et al.: Berlin land-value appraisal — the accuracy evidence, first-hand · Almy: OECD valuation survey — the cost evidence · Hefferan & Boyd: Australian mass appraisal — revealed taxpayer acceptance
• Bencure et al.: iLVM, Baybay City, Philippines — the developing-country / thin-data case · Barr, Smith & Kulkarni: What's Manhattan Worth? — vacant-land sales in the densest US market
• Land Value Tax · Estonia
• Mass Appraisal Methods (CAMA, Hedonic Regression, Land/Building Separation)
• Narrative: The Tax You Can't Dodge — where under-assessment (not evasion) is the real leak

Sources

1. Lars Doucet (2022), "Does Georgism Work? Part 3: Can Unimproved Land Value Be Accurately Assessed?", Astral Codex Ten — wiki summary · original — used for the evidence that mass-appraisal methods do separate land from improvements accurately in practice.
2. Kumar et al. (2020), "Land and building separation based on Shapley values," Humanities and Social Sciences Communications (Nature). Article — used for a formal method of decomposing property value into land and building components.
3. Lincoln Institute of Land Policy — assessment research. wiki summary — used for the body of assessment research showing land-value estimation is a solved practical problem in many jurisdictions.