Move the sliders and watch Scotland's fiscal trajectory respond. The starting point is GERS 2025-26, and every figure is in today's prices. The map turns blue when Scotland's deficit is smaller than it would be staying in the Union. The early years are deliberately hard: transition costs and borrowing weigh on the first years, then tax reform, a consolidation package, EU access and growth take hold. Try the pessimistic scenario: if everything disappoints at once, the numbers do not work without further action, and the model says so.
An analytical tool with stated assumptions, not an audited forecast. The methodology is one click away.
Starting point. GERS 2025-26: a deficit of £25.3bn (10.9% of GDP), which already includes Scotland's geographical share of North Sea revenue. Two adjustments are made: defence at the chosen share of GDP instead of the £5.2bn GERS allocation, and £0.35bn of UK central administration. Debt interest (£8.9bn in GERS) is removed and recalculated explicitly. Everything is in constant 2025-26 prices.
Primary balance (everything except debt interest) = the adjusted starting gap, held at a constant share of the economy + net new land and property tax revenue + tax on extra growth (38% of the additional output) + restraint already planned across the UK and carried forward (up to £4bn) + Scotland's own consolidation package (phased in over six years) + returns on seabed leasing and state energy stakes + housing effect − declining North Sea revenue − set-up costs that fade by Year 7 − the net EU budget contribution after accession.
Interest is charged on all debt: the inherited share at the UK's current effective rate (about 3.9%), refinanced into Scottish bonds at 10% a year, and all new borrowing at Scottish yields, which start at the chosen rate and fall by 0.75 points over ten years as credibility builds. Inflation of 2% erodes the real value of the debt.
Tax reform revenue phases in over 6 to 10 years depending on ambition. Net new = gross minus the £6.6bn of taxes replaced.
Wealth fund receives 50% of North Sea revenue, 30% of energy company profit and £1bn a year from Year 5, earning a 3% real return. Contributions are financed by borrowing, so debt is shown net of the fund.
The Union comparison. Scotland's deficit if it stays in the UK is modelled as the OBR's March 2026 UK borrowing path plus the 6.7-point gap between Scotland and the UK in GERS 2025-26. Both improve together if the UK meets its plans.
What the model does not include. The upside from taxing Scottish activity on arm's-length transfer pricing rather than headcount apportionment, any change in spending on new platform commitments beyond the housing programme, and any renegotiation of NATO commitments. Household income is illustrative: GDP uplift × 0.6 labour share × £38,000, the median Scottish household net income (IFS, 2026).