What the Template Contains
Header Data: Contractor, client, project and purchase order (PO) number, billing period, and sequential reference number.
Line Items: For each entry: date, performing worker/employee, service type, detailed description of activity, hours, rate, and total amount.
Footer: Totals, dispute/objection clause, and signature fields for both parties.
Distinction from the Statutory Working Time Record
| Working Time Record / Timesheet | Proof of Activity / Project Timesheet | |
|---|---|---|
| Purpose | Statutory employment law compliance | Commercial invoicing & billing |
| Recipient | Regulatory authorities, HMRC, Health and Safety Executive (HSE) | Client / Customer |
| Content | Daily start time, finish time, rest breaks | Services rendered, duration, project allocation |
| Legal Basis | Working Time Regulations 1998 (WTR), National Minimum Wage Act 1998 | Commercial contract / Master Services Agreement (MSA) |
Both derive from the same underlying time tracking records but serve entirely distinct stakeholders. Attempting to use a single document for both statutory compliance and client billing is rarely an adequate solution.
The Activity Description Makes the Difference
The commercial defensibility of a proof of activity hinges on a single field.
Unacceptable: "Project work", "Development", "Meeting", "Miscellaneous"
Robust & defensible: "Coordination of interface specification with Logistics department", "Implementation of supplier master data import interface", "Bug triage for sprint acceptance, Ticket 4711"
A rigorous description states the specific deliverable and outcome, not merely a generic category of activity. Taking ten seconds to record precise details determines whether a line item is promptly approved and settled or disputed and deducted from the invoice.
The Dispute and Query Period
The clause in the footer — stating that the record is deemed accepted unless disputed in writing within ten business days — is legally binding only if it is also expressly incorporated into the underlying commercial contract or terms of business. On the form alone, it represents merely a unilateral statement rather than an enforceable agreement.
For Publicly Funded Projects & Grant Claims
For publicly funded projects, government grants (such as Innovate UK awards), and statutory tax relief schemes (such as R&D Tax Relief under the SME or RDEC/ERIS schemes), compliance requirements increase substantially. Funding bodies and HMRC mandate contemporaneous, individual-specific, day-by-day records providing an unambiguous allocation of time to eligible qualifying activities — alongside a clear demarcation from non-qualifying business tasks performed by the same individual.
Estimated or retrospective percentage allocations across projects are routinely rejected during HMRC audits and grant verifications.
Document Retention & Tax Compliance
As the primary factual documentation supporting a commercial invoice, a signed proof of activity forms an essential accounting voucher. Statutory record-keeping obligations apply:
- HMRC & Companies Act 2006: Accounting, VAT, and invoice records must be retained for at least 6 years from the end of the last financial year.
- National Minimum Wage Compliance: Complete time records must be preserved for at least 6 years to prove compliance with statutory wage floors.
- Making Tax Digital (MTD) & Electronic Records: Digital records must maintain integrity, auditability, tamper-resistance, and machine-readability.
Best Practice: Generate Directly from Time Tracking
The proof of activity should never be compiled manually; rather, it should be generated automatically from approved, timestamped time tracking records. This eliminates duplicate administrative labour and ensures that client billing and internal payroll records rely on identical, audit-proof data.