Do Richer Countries Collect Higher Tax Revenue? (18-Country Data)

What we examined

This analysis looks at three aligned readings for 2022 across the 18 countries in the CivlensAI dataset: tax revenue as a share of GDP and GDP per capita, both from the World Bank, and the Human Development Index from UNDP. Countries are matched on ISO codes, and every country in the sample has a value on all three indicators, so nothing was excluded.

The question is whether a larger economy — or a higher development score — goes along with a larger share of output collected as tax revenue. That relationship is not guaranteed: tax share reflects policy choices and the structure of an economy, not just its size.

Because the three values come from two different publishers with independent methodologies, they are compared here as published figures rather than as one unified account.

Tax share rises only weakly with income

Across the sample, the relationship between tax share and GDP per capita is weak. The Spearman rank correlation is 0.32, and the Pearson correlation on the raw values is 0.31. Measured either way, where a country falls on income says little about how large its tax share will be.

The relationship is not monotonic even at the top. The four highest-income economies by GDP per capita — Norway, Switzerland, Singapore, and the United States — sit at tax shares of 31.4%, 18.4%, 13.5%, and 19.6% respectively. Only Norway is above the sample midpoint of roughly 24%.

Finding 1 — The highest earners are not the highest taxpayers

Singapore has the third-highest GDP per capita in the sample ($82,807) and the second-lowest tax share (13.5%). The United States records the fourth-highest GDP per capita ($76,329) with a tax share of 19.6%, below the sample midpoint.

The three highest tax shares belong to Canada (33.6%), Norway (31.4%), and France (31.3%). Of these, Norway holds the top spot on income, but Canada ranks 7th and France 10th on GDP per capita. High tax share in this sample is not a feature of the very highest earners.

Finding 2 — Tax share and development are only moderately related

Compared with the development-adjacent measure, tax share tracks HDI more closely than it tracks income, but still only moderately. The Spearman correlation between tax share and HDI is 0.40.

That is weaker than the relationship this dataset shows between GDP per capita and HDI, whose Spearman correlation is 0.86. How much a country collects in tax has a weaker link to its development score than how much it produces per person — a reminder that government revenue and development outcomes are connected through many intermediate steps this analysis does not measure.

Finding 3 — Nearly identical development, tax shares more than two-fold apart

Singapore and the Netherlands sit almost side by side on development — HDI of 0.939 and 0.944 — yet their tax shares are 13.5% and 28.2% respectively. Two economies with effectively the same development score collect tax revenue at more than double the share of GDP.

Switzerland and Canada extend the same point: both hold high development scores (0.955 and 0.935) while their tax shares differ by 15.2 percentage points. Across the sample it is Singapore (13.5%, HDI 0.939) and Canada (33.6%, HDI 0.935) that hold the widest tax-share gap between two high-development economies — 20.1 percentage points with development scores only 0.004 apart.

Why this does not establish causation

Everything above describes how published tax, income, and development figures sit relative to one another in one year for eighteen countries. Nothing here shows that tax policy causes development outcomes, or that a given tax share is responsible for a country’s position on HDI.

Tax share is the product of many factors this analysis does not control for — the mix of government functions, the structure of the tax base, demographic and regional circumstances. These observations are a reason to examine more data, not conclusions about what any country should do.

Limitations

• Small sample: 18 economies, treated as illustrative rather than representative of all countries.
• Observational single-year cross-section (2022): no trends, no controls, and no basis for causal inference.
• Tax revenue as a share of GDP is a ratio of two published aggregates; it reflects policy and economic structure jointly and does not isolate either.
• Two publishers (World Bank for tax and GDP, UNDP for HDI) with independent methodologies and release schedules.
• A tax-to-GDP ratio can move when the numerator, the denominator, or both change; changes in one are not separable here.
• Descriptive correlations in an 18-country sample can shift materially with different samples or years.

Data and Methodology

This analysis uses indicator data already presented on CivlensAI. How that data is collected, organized, and updated is described on the Methodology page.

Sources

• World Bank Open Data
• UNDP Human Development Report

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