3.7 Full Tax Powers and System Design

What tax powers would Scotland have?

An independent Scotland would control all major taxes—income tax, corporation tax, VAT, a National Insurance equivalent, capital taxes, and the remaining smaller taxes. The tax system would be redesigned for simplicity, competitiveness, and revenue stability, with an early priority on reducing complexity and ensuring the tax base is broad enough to fund public services sustainably. Changes would be phased to avoid disruption, with clear transitional rules for existing taxpayers and businesses.

Full tax powers are central to independence. They are also a central responsibility. The opening fiscal position described earlier in this part cannot be closed by monetary policy under sterlingisation; it must be closed by a combination of growth, prioritisation of spending, and a tax system that raises adequate revenue on a sustainable basis. Powers without a workable collection system, or reforms that destabilise the tax base in the first years, would worsen the problem the powers are meant to help solve.

The main design choices are continuity of liability on day one, phased structural reform, and operating tax policy within the fiscal rules rather than outside them. The main constraints are administrative capacity during the handover from HMRC, the mobility of some tax bases, and the political temptation to cut rates without broadening the base or to promise revenue that the system cannot yet deliver. This section sets out the scope of powers, the principles for redesign, the transition mechanics and the link to the wider fiscal framework.

Full control over taxation is a defining fiscal attribute of an independent state. Under the present settlement, Scotland already sets the rates and bands of income tax on non-savings, non-dividend income and controls several smaller taxes. Yet, the major bases — corporation tax, VAT, National Insurance, capital gains, inheritance tax and most other capital and excise taxes — remain reserved. Independence would remove those residual constraints and vest complete taxing authority in the Scottish Parliament. That authority is both an opportunity and a responsibility. The opportunity is to redesign the system for greater simplicity, a broader base, and structures better suited to a small advanced economy. The responsibility is to raise, on a sustainable basis, the revenue required to fund public services within the legislated fiscal rules and the medium-term fiscal plan.

This section sets out the scope of the powers that would transfer, the principles that would guide redesign, the sequenced approach to implementation that prioritises continuity of liability and collection on Independence Day, and the institutional arrangements required for a functioning Scottish revenue authority. It does so without claiming that full powers automatically close the opening structural deficit, without promising that rate reductions on mobile bases can be financed without behavioural or base consequences, and without softening the operational risks of the handover from HMRC. Tax policy would operate inside the fiscal rules, under independent scrutiny, and subject to honest costings. Continuity of existing taxpayer obligations and of revenue flow is the default on day one; structural reform follows on a planned timetable with adequate notice and transitional protections.

The design choice is deliberate. A sudden, comprehensive rewrite of the tax code on Independence Day would maximise confusion, compliance failure and revenue risk at the precise moment when fiscal credibility is most valuable. Phased reform under clear principles, with continuity as the starting point, reduces that risk while still allowing the Parliament to exercise its new powers.

Current Position and Legal/Institutional Baseline

Under the Scotland Act and the fiscal framework that implements it, the Scottish Parliament has partial control over income tax and full control over Land and Buildings Transaction Tax, Landfill Tax, and the devolved aspects of council tax and non-domestic rates. Corporation tax, VAT, National Insurance contributions, capital gains tax, inheritance tax, most excise duties and the remaining capital and environmental taxes are reserved to the UK Parliament. Revenue Scotland already administers the fully devolved taxes. HMRC administers the reserved taxes and the Scottish income-tax rates through the existing UK systems.

The legal baseline on independence would change. The independence settlement and the interim constitution would vest the Scottish Parliament with unrestricted taxing power. That power would include the authority to set, reform, introduce, or abolish any tax; define the base, rates, reliefs, and administration of each tax; and create new taxes if the Parliament so decides. Detailed tax law would be Scottish primary and secondary legislation. The residual UK statutory constraints would fall away.

The administrative baseline is equally important. Collecting the currently reserved taxes depends on HMRC systems, data, and staff. A Scottish revenue authority would need to assume those functions. Revenue Scotland provides an existing institutional core for the taxes it already administers; expanding to the full tax base requires additional capacity, data migration, IT systems, and specialist expertise. Transitional cooperation with HMRC is the practical route to protecting revenue continuity during the handover; the legal authority to collect would rest on Scottish legislation from Independence Day regardless of the state of that cooperation.

Mechanism and Delivery

The mechanism for transferring powers is the independence settlement, together with the interim constitution and the first tranche of Scottish tax legislation. On Independence Day, the existing body of tax rules would continue to apply to taxpayers in Scotland unless and until amended by the Scottish Parliament. Continuity of liability, filing obligations, payment schedules and enforcement is the default. Clear transitional regulations would specify how ongoing enquiries, appeals, instalment arrangements, and relief claims are to be treated; which authority is owed the tax; and how dual-running or data-sharing arrangements with HMRC operate during the handover period.

Structural reform would follow a published timetable. Early priorities would focus on measures that reduce unnecessary complexity, broaden the base where reliefs no longer serve a clear purpose, and improve administrability, provided those measures can be implemented without destabilising revenue or creating large compliance shocks. More far-reaching changes to rates, bands or the structure of major taxes would be introduced with adequate notice, consultation, guidance and, where necessary, staged commencement. The independent fiscal institution would cost major proposals and assess their consistency with the fiscal rules and the medium-term plan before locking them in.

A Scottish revenue authority would be established, building on the existing Revenue Scotland organisation, systems and staff. Its mandate would cover assessment, collection, enforcement and taxpayer service for the full range of taxes. The authority would seek transitional cooperation agreements with HMRC for data access, dual-running of systems, staff secondment or knowledge transfer, and the orderly migration of taxpayer records. Where cooperation is limited, the authority would still assert collection powers under domestic law, but operational risk and cost would rise. Contingency planning for imperfect cooperation — including accelerated recruitment, alternative IT pathways and prioritised collection of the largest revenue streams — is therefore part of readiness.

Tax policy itself would be made within the binding fiscal rules. Revenue forecasts would be produced or scrutinised by the independent fiscal institution. Decisions to change rates or reliefs would be assessed for their impact on the deficit path, the debt objective and long-term sustainability. Tax measures would appear in the medium-term fiscal plan as instruments for meeting the legislated targets, not as free-standing political announcements detached from the arithmetic.

Continuity Design

Continuity of tax liability and collection is a design requirement parallel to continuity of pensions, benefits and deposit protection. On Independence Day, a taxpayer who was liable under UK rules remains liable under the continuing Scottish application of those rules until the Scottish Parliament changes them. Filing deadlines, payment dates, interest and penalty regimes, and existing relief claims continue unless expressly modified. Businesses and individuals are not required to re-register or to adopt new computational methods overnight.

The transitional arrangements with HMRC and Revenue Scotland's expansion into a full revenue authority secure continuity of the administrative relationship. Taxpayer records, payment histories and ongoing compliance activity transfer under controlled protocols. Where dual-running is agreed, taxpayers continue to interact with familiar channels while Scottish systems assume full responsibility. The legal continuity of Scots law and of the court system ensures that disputes over tax liability remain justiciable without a gap in enforcement or appeal rights.

The design therefore protects ordinary taxpayers and businesses from abrupt discontinuity while still allowing the Parliament to exercise its new powers on a planned timetable. Any break in collection or in the clarity of liability would be a failure of transition management, not an inevitable consequence of the transfer of powers.

Constraints and Trade-offs

Legal constraints

The vesting of full taxing power must be clear in the independence settlement and the interim constitution so that the legal authority of the Scottish revenue authority is beyond doubt from day one. Transitional regulations must define the boundary between continuing UK obligations and new Scottish ones with precision sufficient to withstand challenge. Double-taxation arrangements with the continuing United Kingdom and with other jurisdictions will require negotiation or transitional coverage to prevent gaps or overlaps that harm taxpayers or revenue. The mobility of certain bases—particularly corporation tax and the taxation of higher earners—means large unilateral divergences can produce behavioural responses that the legislation itself cannot prevent; the legal power to set rates does not eliminate the economic constraint.

Fiscal constraints

Full powers increase the ability to adjust the revenue path, yet they do not create revenue by the mere fact of transfer. Aggressive rate cuts on mobile bases without corresponding base-broadening or spending adjustment would widen the deficit relative to the path required by the fiscal rules. Conversely, sharp increases that trigger significant behavioural change can fail to deliver the expected yield. The independent fiscal institution’s costings and the medium-term plan exist to make those trade-offs visible before decisions are taken. The opening structural deficit remains a binding constraint: tax policy is one instrument among others for closing it, not a substitute for prioritisation of spending or for growth.

Operational constraints

Standing up a revenue authority capable of administering the full tax base requires data migration, IT systems, specialist staff and operational protocols that cannot be created overnight. The 18–24 month transition window is already ambitious for the complete handover of HMRC functions. Prioritisation of the largest revenue streams, dual-running where agreed, and contingency capacity for imperfect cooperation are therefore essential. Complexity in the inherited tax code raises the operational burden of both continuity and reform. A theoretically attractive redesign that exceeds administrative capacity in the early years becomes a revenue and compliance risk. Design choices must therefore be filtered through the test of collectability.

Political constraints

Tax policy is inherently political. The temptation to announce short-term popular rate reductions, or to promise revenue yields that optimistic behavioural assumptions cannot support, is predictable. Subordinating tax decisions to fiscal rules and independent costings raises the cost of such announcements, but it cannot eliminate the underlying political incentive. Sustaining a broad political understanding that competitiveness and revenue adequacy must be pursued within the fiscal framework, rather than as alternatives to it, is part of managing the transition and the early years of independence.

Time constraints

The legal transfer of powers and the continuity of collection must be effective on Independence Day. The expansion of the revenue authority, the migration of data and the preparation of transitional regulations must therefore be completed within the transition timetable. Major structural reforms cannot all be delivered in the same window without overload; they require a sequenced programme with realistic lead times for consultation, legislation, systems change and taxpayer guidance. The medium-term fiscal plan provides the vehicle for that sequencing. Compressing comprehensive reform into the immediate post-independence period raises operational and revenue risk at the moment when credibility matters most.

Consistency with the Wider Framework

Full tax powers are the revenue counterpart of the expenditure and borrowing constraints contained in the legislated fiscal rules. They supply the instruments through which the medium-term fiscal plan can adjust the path from the opening deficit toward sustainability. Revenue forecasts and major tax measures fall under the scrutiny of the independent fiscal institution, ensuring independent costings and public testing of consistency with the rules. The Scottish revenue authority is one of the day-one institutions whose readiness underpins the entire fiscal architecture.

Tax policy interacts with the Wealth Fund only at the margin: the Fund is capitalised from a defined share of resource revenues, not from the broad tax base, and withdrawals from the Fund enter the budget under the same rules that govern other receipts. Continuity of tax liability and collection is consistent with the wider continuity design for pensions, benefits, contracts and deposit protection. Under sterlingisation, taxes continue to be levied and paid in sterling; domestic obligations face no currency-conversion friction. The long-term nuclear basing agreement and the Common Travel Area-style arrangement for free movement of people protect elements of the economic and labour-market base that support the tax system. The non-EU stance removes one potential source of short-term regulatory disruption to the tax treatment of cross-border activity. In every case, tax powers operate inside the framework rather than as a parallel domain exempt from its constraints.

Hardest Critiques and Direct Responses

Feasibility

The legal transfer of full taxing power is straightforward once the independence settlement and interim constitution are in place. The operational transfer of collection is more demanding but feasible within the transition window if prioritised, if transitional cooperation with HMRC is secured, and if contingency arrangements for imperfect cooperation are prepared. Phased structural reform is more feasible than a comprehensive rewrite on day one. International experience of tax administration in small advanced economies shows that full domestic collection is achievable; the constraint is preparation and sequencing, not an inherent incapacity.

Cost and fiscal burden

Standing up and running a full revenue authority is a real cost that must be funded inside the medium-term plan. Failure to fund it adequately would threaten the revenue side of the fiscal framework. The larger fiscal question is the tax system's yield. Full powers do not automatically increase revenue; they increase the ability to adjust rates, bases and reliefs. Choices that narrow the base or that trigger large behavioural responses can reduce yield. Choices that broaden the base and improve compliance can support the adjustment path. The independent fiscal institution’s costings exist to make those effects visible before decisions are locked in.

Dependence on agreement

The legal power to tax is domestic. Operational continuity of collection benefits materially from cooperation with HMRC on data, dual-running and knowledge transfer. If cooperation is limited, Scotland would still assert collection powers under domestic law, but operational risk, cost and the probability of revenue interruption would rise. Contingency planning for that scenario is therefore required. Double-taxation arrangements with the continuing United Kingdom will also require negotiation; transitional coverage can bridge the period until a durable agreement is reached.

Transition risk

The principal risks are interrupted collection, confused filing obligations, disputes over which authority is owed tax, and administrative overload if major reforms are attempted too quickly. Mitigation is default continuity of the existing rules, explicit transitional regulations, public guidance issued in advance, dual-running where agreed, prioritisation of the largest revenue streams, and a sequenced reform timetable that respects administrative capacity. Another risk is political pressure to announce large rate changes before the revenue authority and the independent costings capacity are ready; subordinating tax policy to the fiscal rules and the medium-term plan reduces that risk but does not eliminate it.

Alternatives (status quo and previous proposals)

Retaining UK tax law indefinitely without Scottish power to change it is incompatible with independence and is rejected. Rewriting the entire tax code on Independence Day maximises disruption, compliance failure and revenue risk; it is rejected in favour of continuity of rules followed by phased reform. Aggressive rate cuts without base-broadening or corresponding spending adjustment would widen the deficit path unless offset elsewhere and are incompatible with the fiscal rules as designed; the design rejects this as a default strategy. Assuming that tax competition alone will fund the opening gap is unsupported by the scale of the inherited position and is rejected. The design chooses full powers, continuity on day one, phased reform under clear principles, and tax policy operating within the fiscal framework.

Political and public credibility

The claim most likely to be called unrealistic is that Scotland can both undercut the rest of the United Kingdom on headline tax rates and sustain higher public spending, or that a new revenue authority will collect every pound without friction in the early years. The precise answer is that this framework subordinates tax choices to the legislated fiscal rules and the medium-term plan; competitiveness is a design principle pursued inside that constraint, not a promise of a free lunch; and collection capacity is treated as a critical-path item with transitional cooperation sought and domestic contingency required. Credibility rests on phased reform, independent costings of major measures, and revenue that actually arrives rather than revenue that is assumed. The first budgets and the first independent assessments will be the observable test.

Position Summarised

Independence would give Scotland full control over all major taxes, including income tax, corporation tax, VAT, social security contributions, capital taxes and the remaining smaller taxes. The system would be redesigned around principles of simplicity, competitiveness, revenue stability and adequacy, fairness, and administrability, with a broad base capable of funding public services sustainably within the fiscal rules. Changes would be introduced in phases: existing rules continue on Independence Day unless and until amended, clear transitional protections apply, and major structural reforms follow a published timetable with adequate notice.

Tax policy would operate within the legislated fiscal rules, under the scrutiny of the independent fiscal institution, and as an instrument of the medium-term fiscal plan. A Scottish revenue authority, building on Revenue Scotland, would assume collection of the full tax base, supported by transitional cooperation with HMRC where agreed and by domestic contingency arrangements. Full powers bring both the opportunity to improve the system and the responsibility to raise the revenue that sustainable public services require. Day-one continuity of liability and collection is the default; structural reform follows under controlled conditions.

Conclusion

Full tax powers are necessary for fiscal sovereignty and insufficient on their own. They must be paired with a revenue authority that can collect, a phased reform path that does not break compliance or interrupt revenue, and subordination to the fiscal rules that define sustainability. This framework therefore vests complete taxing authority in the Scottish Parliament, keeps existing rules in force until Scotland changes them, and treats tax policy as an instrument of the medium-term plan rather than a parallel domain exempt from arithmetic discipline.

The opening deficit will not close because the Parliament possesses the power to set rates. It will close only if that power is used inside a credible framework — a broad and administrable base, honest independent costings, collection systems that work, and consistency with the deficit path and debt objective. The final section of this part of the series turns those requirements into a published multi-year plan: how the gap is closed in practice, year by year, under the rules, under independent scrutiny, and with the tax system operating as a stable contributor to the adjustment rather than as a source of additional uncertainty.

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This analysis forms part of People’s Future Scotland: The Independence Debate, a non-party framework examining the practical design of independence. Each section is written to withstand professional scrutiny and to prioritise mechanism, constraint and continuity over aspiration.