UK Tax Revenue Dynamics 2024-2025
Analysis Date: 14 December 2025
Executive Summary
The UK tax system is currently displaying classic Laffer curve dynamics, where increasing tax rates are producing diminishing or even negative returns. Despite aggressive rate increases and threshold freezes across multiple tax categories, government revenues are falling significantly short of projections, with structural behavioural changes threatening long-term fiscal sustainability.
The Laffer Curve: Theoretical Foundation
The Laffer curve, popularized by economist Arthur Laffer in the 1970s, illustrates the relationship between tax rates and government revenue. The core principle demonstrates that at both zero percent and 100 percent tax rates, government revenue would be zero. At zero percent because no tax is collected, and at 100 percent because there is no incentive to work or produce.
Between these extremes exists an optimal tax rate that maximizes revenue. Beyond this point, the negative behavioural effects of taxation, including reduced work effort, decreased investment, tax avoidance, and economic migration, begin to outweigh the increased rates. The critical challenge is determining where this inflection point lies for any given economy and tax structure.
Current UK Tax Situation: The Evidence
The Revenue Shortfall
The Office for Budget Responsibility reported in March 2025 that public sector receipts for 2024-25 came in £7.5 billion (0.6 percent) lower than projected just five months earlier in October 2024. This represents the largest downward revision to receipts between autumn and spring forecasts since 2012.
The shortfall was concentrated in precisely those areas where behavioural responses to high tax rates are most pronounced:
Self-assessed income tax
Capital gains tax
Corporation tax from small companies
Income from partnerships and dividend income
Capital Gains Tax: A Clear Case Study
Capital gains tax provides perhaps the clearest evidence of Laffer curve dynamics. Despite successive reductions in the annual exempt amount and rate increases, receipts have declined dramatically:
Tax Year
CGT Receipts
Change
2022-23
£16.9 billion
—
2023-24
£14.5 billion
-14.2%
2024-25
£13.7 billion
-5.5%
This 19 percent decline over two years occurred despite government efforts to increase revenue through tighter rules. In October 2024, the government further increased CGT rates from 10 percent and 20 percent to 18 percent and 24 percent respectively, likely exacerbating the revenue decline.
The Exodus of Mobile Capital and Talent
One of the most significant behavioural responses to high taxation is economic migration. The UK is experiencing this phenomenon at an accelerating pace. During the 2024-25 tax year, approximately 1,800 non-domiciled individuals left the UK, representing a 50 percent increase over the Office for Budget Responsibility’s forecast of 1,200 departures.
These non-doms are typically highly mobile, wealthy individuals who contribute disproportionately to tax revenues. Their departure is driven by multiple factors:
Abolition of non-dom status from April 2025
Increased capital gains tax rates
Changes to inheritance tax treatment of offshore trusts
Introduction of carried interest taxation at higher rates
UK’s highest tax burden in decades
Globally, a record 142,000 millionaires are projected to relocate internationally in 2025. The UK is experiencing net outflows alongside other high-tax European nations including France, Germany, and Spain. Meanwhile, lower-tax jurisdictions such as the United Arab Emirates are seeing record inflows, with Dubai alone expected to welcome 9,800 millionaires this year.
Small Business Tax Base Erosion
The OBR analysis revealed that the revenue shortfall was particularly pronounced in small company corporation tax, income from partnerships, and dividend income. The explanation provided points to structural economic pressures:
The high inflation and interest rates in 2023-24 decreased the profitability of small businesses by more than anticipated. This high inflation was externally driven and so for many small businesses increased costs by more than revenues.
This represents a classic tax base erosion scenario. While rates remained high or increased, the underlying economic activity that generates taxable income contracted. Small businesses, which represent approximately 93 percent of UK businesses, face compounding pressures:
Employer National Insurance contributions increasing from 13.8 percent to 15 percent from April 2025
The threshold at which employers pay NI contributions dropping from £9,100 to £5,000
National Living Wage increasing to £12.21 per hour
Frozen income tax thresholds creating fiscal drag
High inflation increasing operating costs
Government Response and Policy Measures
Tax Increases Implemented
The government’s response to fiscal pressures has been to implement a wide array of tax increases:
Tax Category
Previous
Current
CGT Lower Rate
10%
18%
CGT Higher Rate
20%
24%
Employer NI Rate
13.8%
15%
Employer NI Threshold
£9,100
£5,000
Carried Interest Tax
28%
32%
SDLT Surcharge
3%
5%
Additionally, the government has frozen income tax thresholds until 2030, creating substantial fiscal drag as inflation pushes more taxpayers into higher brackets without any increase in real income.
The projected revenue from employer NI increases alone is £23.7 billion in 2025-26. However, this projection assumes no significant behavioural response, an assumption that appears increasingly questionable given the evidence of tax base erosion across other categories.
The Corporate Tax Roadmap
In October 2024, alongside the Autumn Budget, the government published a corporate tax roadmap intended to provide businesses with certainty. Key commitments include:
Capping corporation tax at the current 25 percent rate
Retaining full expensing for capital investments
Maintaining the current losses regime
Consulting on simplification of capital allowances
While the roadmap provides some stability for direct corporation tax, it does nothing to address the mounting burden of employer National Insurance contributions, business rates, or other levies that affect corporate profitability. The overall message is one of contradictions: stability in some areas while implementing aggressive increases in others.
Economic and Behavioural Impacts
Labour Market Effects
The increase in employer National Insurance contributions from 13.8 percent to 15 percent, combined with the reduced threshold from £9,100 to £5,000, represents a significant shock to the labour market. Industry experts warn of multiple potential consequences:
Reduced wage increases for employees as employers absorb higher costs
Job losses, particularly in low-wage sectors
Acceleration of automation and technology adoption to replace workers
Offshoring of work to lower-cost jurisdictions
Higher prices passed on to consumers
The concern is particularly acute in retail, hospitality, and leisure sectors where profit margins are thin and labour costs represent a substantial proportion of operating expenses. These sectors employ millions of workers, many at or near minimum wage levels.
Investment and Entrepreneurship
Higher capital gains tax rates directly impact investment decisions and entrepreneurial activity. The dramatic increases in CGT rates for Business Asset Disposal Relief provide a telling example:
April 2024: 10 percent rate
April 2025: 14 percent rate
April 2026: 18 percent rate (projected)
This 80 percent increase over two years fundamentally alters the economics of building and selling businesses in the UK. Entrepreneurs and investors now face substantially reduced after-tax returns, which affects:
Willingness to start new businesses
Decisions about where to locate business headquarters
Timing of business sales and exits
International investment flows into UK ventures
Personal domicile decisions for founders and investors
Tax Avoidance and Restructuring
As tax rates increase, the incentive for tax planning, avoidance, and business restructuring intensifies. The OBR noted that some of the corporation tax shortfall may be attributable to timing strategies employed by businesses, including the deferral of loss write-offs to take advantage of rate changes.
More broadly, high effective tax rates encourage:
Incorporation and profit retention to avoid dividend tax
Pension contribution maximization for tax relief
Capital structuring to minimize taxable gains
Use of trusts and offshore structures where permitted
Relocation of domicile and residency status
Each of these behaviours represents economic resources diverted into tax planning rather than productive activity, creating deadweight loss for the economy while simultaneously eroding the tax base.
The Structural Revenue Problem
OBR Assessment of Structural vs Temporary Shortfall
Of the £7.5 billion revenue shortfall, the OBR classified only £4.5 billion as structural, meaning it would persist into future years. The remaining £3 billion was attributed to temporary factors expected to reverse. This assessment, however, may prove optimistic.
The OBR’s assumption of recovery depends on:
Small business profitability returning to trend
Capital gains tax reverting to historical patterns
No further acceleration of wealthy individual emigration
Behavioral responses stabilizing rather than intensifying
Each of these assumptions is questionable given the policy trajectory. With further tax increases planned, including the full implementation of carried interest taxation within the income tax framework in April 2026, and continued threshold freezes until 2030, the behavioural pressures are more likely to intensify than moderate.
The Compounding Effect
The current situation demonstrates a classic policy trap. As revenues fall short, the government faces pressure to increase rates further or expand the tax base, which in turn accelerates behavioral responses and emigration. This creates a negative spiral:
Tax increases implemented to close fiscal gap
Behavioral responses reduce revenue below projections
New fiscal gap emerges larger than the original
Further tax increases considered or implemented
Cycle repeats with diminishing effectiveness
Breaking this cycle requires acknowledging that the UK may be operating on the wrong side of the Laffer curve for certain taxes, particularly those affecting mobile capital and highly skilled individuals.
International Context and Competition
The UK does not operate in isolation. Tax policy must be understood in the context of international tax competition. While the UK implements aggressive tax increases, competitor jurisdictions are moving in opposite directions:
Jurisdiction
Tax Approach
UAE / Dubai
Zero income tax, golden visa programs, expected net inflow of 9,800 millionaires in 2025
Portugal
Favorable tax regimes for new residents, attracting wealthy Europeans
Greece
Golden visa programs, competitive tax treatment for high-net-worth individuals
Ireland
12.5% corporation tax rate (though seeing some outflows), competitive for businesses
UK
25% corporation tax, 15% employer NI, 24% CGT, non-dom abolition, net outflows
This competitive disadvantage is not lost on businesses and high-net-worth individuals. The decision to relocate is increasingly straightforward when alternative jurisdictions offer substantially lower tax burdens combined with high quality of life, political stability, and modern infrastructure.
Conclusions and Implications
Evidence of Laffer Curve Dynamics
The evidence strongly suggests that the UK has moved beyond the revenue-maximizing point of the Laffer curve for several key taxes:
Capital gains tax revenues declining despite rate increases and base expansion
Wealthy individuals emigrating at 50 percent above forecast rates
Small business tax base eroding under compound pressures
Overall revenue shortfall of £7.5 billion despite aggressive rate increases
Structural component of shortfall likely underestimated by OBR
These are precisely the patterns predicted by Laffer curve theory when tax rates exceed optimal levels. The behavioral responses, including reduced economic activity, increased avoidance, and outright emigration, are overwhelming the mechanical revenue increases from higher rates.
The Path Forward
The current trajectory is unsustainable. Continuing to raise rates in response to revenue shortfalls will likely accelerate the negative spiral. Alternative approaches that merit consideration include:
Comprehensive review of which taxes have exceeded revenue-maximizing rates
Strategic rate reductions for highly elastic tax bases (CGT, carried interest)
Broadening the tax base while lowering marginal rates
Addressing spending growth rather than relying solely on tax increases
Considering UK competitiveness in international tax competition
Implementing measures to retain mobile talent and capital
The fundamental insight of the Laffer curve is that beyond a certain point, attempting to extract more revenue through higher rates becomes counterproductive. The UK appears to have reached that point for multiple taxes simultaneously, creating a fiscal crisis that cannot be resolved through further rate increases.
Final Assessment
The Laffer curve is not just theoretical economics. It is happening in real time in the UK tax system. The government is discovering what happens when tax rates cross the revenue-maximizing threshold: the tax base shrinks faster than the rates rise, wealthy individuals and businesses relocate, and the fiscal situation deteriorates despite aggressive tax policy.
The £7.5 billion revenue shortfall for 2024-25 is likely just the beginning. Unless policy changes direction, the gap between projected and actual revenues will continue to widen as behavioral responses intensify and the most mobile segments of the tax base continue their exodus.
The evidence is clear: the UK has moved to the wrong side of the Laffer curve for key taxes. The question now is whether policymakers will acknowledge this reality and adjust course, or whether they will continue pursuing higher rates in the face of diminishing and eventually negative returns.
Data Sources and References
Office for Budget Responsibility
The in-year shortfall in 2024-25 receipts and its impact on the forecast, March 2025
HM Revenue and Customs
Tax receipts and National Insurance contributions for the UK, 2024-25
House of Commons Library
Tax statistics: an overview, August 2025
Chamberlain Walker Consultancy
Non-domiciled individual departures analysis, 2024-25
Henley and Partners
Global millionaire migration trends, 2025
UK Government
Autumn Budget 2024, October 2024
Corporate Tax Roadmap, October 2024
Direct effects of illustrative tax changes bulletin, June 2025
Professional Services Firms
Blick Rothenberg: Record 2024 tax receipts analysis
Deloitte: UK Tax - Navigating 2025’s Changes
Pinsent Masons: UK Budget analysis
Friend Partnership: HMRC tax receipts 2024-25 summary
Audit Consulting Group: United Kingdom Taxation Trends 2000-2024
Document prepared: 14 December 2025