OBR July 2026: UK Debt Path to 300% of GDP — What SMEs Should Watch

On 7 July 2026 the Office for Budget Responsibility published its annual Fiscal Risks and Sustainability report — the UK’s latest fiscal forecast shaping budget and fiscal statement debate for the rest of 2026. The central message is stark: without further fiscal action, debt moves onto an unsustainable and ever-rising path in nearly every scenario the OBR modelled.

For UK businesses and taxpayers, the July 2026 OBR forecast frames the policy choices ahead of the next spending review and Budget — ageing demographics, health and defence costs, and weakening emissions-related receipts all push spending up while the tax base faces long-run pressures from frozen thresholds and declining fuel duty.

Under the OBR's baseline scenario, public sector net debt rises from around 95% of GDP in 2030–31 to roughly 300% of GDP by 2075–76. Rising borrowing in each projected year compounds interest costs, which themselves grow as a share of GDP.

The OBR stresses these paths are not forecasts — future governments would intervene before debt reached explosive levels. But the report argues unsustainable outcomes that may not materialise for decades are a challenge for policymakers today, not a distant theoretical risk.

Primary government spending — excluding debt interest — is projected to rise from 40% of GDP in 2030–31 to 49% by 2075–76, driven by health, social care, state pensions, defence, and net-zero investment.

To prevent debt exceeding its forecast 2030–31 level of 95% of GDP, the OBR estimates the primary balance must improve by 3.8% of GDP through a permanent one-off adjustment in 2031–32. That is roughly one-third larger than the tightening the government plans over the coming five years.

For context, 3.8% of GDP in 2030–31 is approximately equivalent to total onshore corporation tax receipts or current departmental spending on education — illustrating the scale of tax rises or spending cuts implied by holding debt flat at current levels.

Delaying action makes the problem harder. Postponing adjustment to the 2050s would require an 8% of GDP primary balance improvement — close to the entire health budget — to restore sustainability.

On the revenue side, the OBR examines how an ageing population, AI-driven shifts in the labour share, and declining hydrocarbon use affect the tax base. Fuel duty receipts are projected to fall as electric vehicle adoption reduces diesel miles — a trend already visible in HMRC's monthly bulletins.

Frozen personal tax thresholds — confirmed until 2030–31 — continue to lift income tax receipts through fiscal drag, but the OBR's scenarios show this is insufficient to offset rising spending without additional policy change.

The report also explores alternative scenarios: CPI uprating of tax thresholds would reduce the required tightening to 1.1% of GDP, while higher medium-term deficits plus shocks would push the required adjustment above 8%.

The OBR report does not set immediate tax rates, but it signals the direction of travel for medium-term fiscal policy. Employers should model payroll and corporation tax under scenarios where NIC and income tax thresholds remain frozen and indirect taxes face structural decline.

Sectors dependent on public contracts — health, defence, infrastructure — should expect continued spending growth but also scrutiny on value for money as the government balances demographic pressures against debt limits.

FinnAccountings tracks UK tax liability forecasts against your business income in real time — start a free trial to stress-test cash flow under tighter long-run fiscal assumptions.