7 Mistakes You’re Making with Commercial Property Due Diligence (And How the 2026 Business Rates Reform Affects Your ROI)

Commercial property investment requires a systematic approach to due diligence. Errors in this phase lead to unexpected costs and reduced return on investment (ROI). In 2026, the UK commercial market faces new regulatory requirements and business rates revaluations. This article identifies seven common mistakes in the due diligence process and analyzes the impact of the 2026 Business Rates Reform.

1. Delayed Initiation of Due Diligence

A common error is starting the due diligence process after pricing and funding structures are finalized. Initiating reviews late in the transaction reduces a buyer’s leverage to negotiate price adjustments based on discovered risks.

Professional investors should conduct preliminary checks during the deal sourcing phase. Early assessment allows for the identification of red flags before significant legal and consultancy fees are incurred.

2. Incomplete Audit of Lease Covenants

Investors often fail to perform a detailed audit of existing lease agreements. Overlooking specific clauses can result in limited control over the asset. Key areas for review include:

• Break Clauses: Assessing the probability of a tenant exercising an option to terminate.

• Alienation Clauses: Understanding the tenant's rights to sublet or assign the lease.

• Repairing Obligations: Verifying if the lease is a Full Repairing and Insuring (FRI) lease or if the landlord retains maintenance responsibilities.

Failure to verify tenant quality and payment history also impacts the stability of future cash flows.

3. Disregarding ESG and EPC Compliance

Minimum Energy Efficiency Standards (MEES) continue to evolve. A frequent mistake is failing to account for the capital expenditure (CapEx) required to meet future energy performance targets. Properties failing to reach an EPC 'B' rating by 2030 may become unlettable under proposed regulations.

Due diligence must include an assessment of the current EPC rating and a costed plan for necessary upgrades. This assessment is a standard component of our investment opportunities analysis.

4. Underestimating Structural and Environmental Risks

Skipping or opting for basic building surveys can hide latent defects. Common structural issues include:

• Roof Failures: Identifying aging materials or poor drainage.

• RAAC Planks: Checking for Reinforced Autoclaved Aerated Concrete in older commercial structures.

• Contamination: Investigating historical land use to avoid remediation liabilities.

Environmental liability often stays with the property owner. Professional environmental searches are essential to mitigate this risk.

5. Errors in Verifying Planning and Use Classes

Assuming a property’s current use is legally compliant is a mistake. Investors must verify that the property has the correct planning permission for its intended operation. The UK government’s Use Class Order reforms mean that some transitions between uses are easier, but restrictions may still apply via Article 4 directions.

Lack of compliance can lead to enforcement action from local authorities and prevent future refinancing of the asset.

6. Poor Service Charge Analysis

In multi-tenanted buildings, service charge mismanagement is a risk to ROI. Common errors include:

• Unrecoverable Costs: Identifying costs that the landlord cannot pass on to tenants.

• Sinking Funds: Verifying if sufficient funds exist for major future repairs.

• Historical Disputes: Checking for outstanding disagreements between the landlord and tenants regarding service quality or costs.

An accurate service charge budget is necessary for a precise net income calculation.

7. Miscalculating the Impact of the 2026 Business Rates Reform

The 2026 Business Rates Revaluation took effect on 1 April 2026. Failing to account for new rateable values (RV) and multipliers is a significant oversight for current acquisitions.

The 2026 Revaluation Framework

The Valuation Office Agency (VOA) set the new rateable values based on rental market conditions as of 1 April 2024 (the Antecedent Valuation Date). Nationally, the total rateable value increased by approximately 19.2%.

Multiplier Tiers and ROI Impact

Business rates are calculated by multiplying the RV by a set multiplier. From April 2026, the system uses a tiered approach:

1. Small Properties (<£51,000 RV): Benefit from the lowest multipliers.

2. Mid-Tier Properties (£51,000 - £499,999 RV): Standard multipliers apply.

3. Large Properties (>£500,000 RV): Subject to the highest multipliers (typically between 0.508 and 0.528).

Investors must calculate the "true" holding cost of a property by applying these new rates. If a property's RV has increased significantly, the operational cost will rise, potentially lowering the net yield unless rents also increase.

Transitional Relief

The government implemented a £3.2 billion Transitional Relief scheme to phase in the increases. Caps on annual increases are determined by property size:

• Small properties: 5% cap in the first year.

• Medium properties: 15% cap in the first year.

• Large properties: 30% cap in the first year.

Due diligence should confirm where a property sits within these cycles to forecast cash flow accurately. Detailed information on these changes can be found through the Valuation Office Agency.

Conclusion

Effective due diligence mitigates risk and protects investor ROI. By avoiding these seven mistakes and accounting for the 2026 Business Rates Reform, investors can maintain more predictable portfolios.

Realty Packaging provides support for these processes through our commercial power team. We offer guidance on market analysis and due diligence for various commercial assets.

For more information on commercial property investment strategies, visit our education section.