OECD Delivers Blunt Message on UK Tax System Complexity
The Organisation for Economic Co-operation and Development (OECD) has issued a stark warning to the United Kingdom, emphasizing the urgent need to simplify the tax system to avoid weaker economic growth. This call to action should not be overlooked, as the issue extends far beyond mere complexity on paper. Over the years, the UK has developed a labyrinth of thresholds, tapers, and reliefs that interact in unintended ways, creating distortions that directly impact decisions regarding work, career progression, and investment.
The Punitive £100,000 Threshold and Its Consequences
Nowhere is this distortion more evident than at the £100,000 income mark, where the tax system transitions abruptly from progressive to punitive. Upon crossing this threshold, individuals begin to lose their personal allowance, and for many families, childcare support vanishes entirely. This results in effective marginal tax rates reaching 60 per cent, or 62 per cent when National Insurance contributions are factored in. The OECD has consistently cautioned that such 'kinks' in the tax system discourage people from increasing their earnings, a concern that is now gaining political attention.
Education Secretary Bridget Phillipson has recently acknowledged the severity of the problem, confirming that the £100,000 childcare cliff edge is under review due to its overwhelming complexity for families. Research conducted by IG into the High Earners, Not Rich Yet (HENRY) cohort—those earning between £90,000 and £125,000—reveals how deeply these distortions are affecting mid-career professionals. These individuals are not ultra-wealthy but rather professionals with growing incomes, young families, and investment potential, precisely the group policymakers should rely on to drive long-term economic growth.
Rational Responses to a Flawed System
Instead of propelling growth, many in this cohort are holding back. A staggering 82 per cent report taking deliberate steps to remain below the £100,000 threshold, such as reducing work hours or declining opportunities that would increase their income. This rational response highlights a system where, beyond a certain point, additional effort no longer yields financial benefits. The consequences extend beyond immediate earnings, with nearly half (48 per cent) of surveyed individuals stating they cannot invest sufficiently to build long-term wealth, a figure that rises sharply among households with nursery-age children.
For a government focused on enhancing participation in UK capital markets, this trend is alarming. These households represent a critical pipeline for domestic investment, yet the current tax system is increasingly limiting their ability and willingness to deploy capital. The distortion is starkly illustrated in practical terms: analysis shows that a household with two young children could be over £13,000 worse off next year simply for accepting a routine pay rise that pushes them over the £100,000 threshold, creating what the OECD describes as a 'dead zone' where extra work does not pay.
Exacerbating Factors and Proposed Solutions
This issue has been exacerbated by frozen thresholds, which have silently expanded the problem's reach. Had the £100,000 childcare limit kept pace with inflation since 2013, it would now be closer to £135,000, while the personal allowance taper would begin near £156,000. This represents fiscal drag at its most damaging, pulling more individuals into a system that penalizes progression. The solution is straightforward: allowing thresholds to rise with inflation would alleviate some pressure, and easing the taper would ensure that earning more genuinely improves financial well-being.
Beyond these adjustments, there is a clear opportunity to align tax policy with growth objectives. Implementing a dedicated UK Equities Investment Scheme—offering income tax relief on UK-listed shares held in Individual Savings Accounts (ISAs)—could unlock capital from middle and higher earners. Higher-rate taxpayers could receive up to £8,000 in annual relief while supporting domestic capital formation. Simultaneously, policymakers should safeguard existing tools that households use to navigate the system, such as reconsidering the planned £2,000 cap on National Insurance Contribution-free pension salary sacrifice contributions, which risks undermining a vital mechanism for managing income and avoiding cliff-edge losses.
Broader Implications for Economic Growth
The OECD is correct in highlighting that the structure of the UK tax system is now acting as a constraint on growth. When the incentives within this system begin to influence whether individuals take on more work, pursue career advancement, or invest for the future, the effects ripple far beyond individual households, impacting the broader economy. Michael Healy, UK & Ireland managing director at IG, underscores the urgency of addressing these distortions to foster a more equitable and growth-oriented tax environment.
