Record-keeping requirements for hours and materials are not one law but a set of rules that require businesses to keep verifiable records of time worked and materials used: working time and minimum wage records for employees (2 and 6 years in the UK), HMRC business records (5 to 6 years) and F-gas records (5 years). A digital work order captures all of this without extra paperwork.
Timesheets in the van, supplier delivery notes in the glovebox and a pile of paper on the office desk every Friday. That is still how many installation, construction and service businesses record hours and materials. Until HMRC, an inspector or a main contractor asks for evidence.
This guide covers which rules apply, how long you need to keep what, where record-keeping goes wrong and how to comply without creating more work for your technicians or your office. It focuses on the UK, with notes for businesses operating in the EU.
Note: this guide is a practical overview and not legal or tax advice. Check your own situation with your accountant or trade association.
Which rules require you to record hours and materials?
1. Working Time Regulations
UK employers must keep adequate records to show that employees are not working more than the 48-hour weekly limit unless they have opted out, and that night work limits are respected. These records must be kept for 2 years.
2. National Minimum Wage records
Employers must be able to prove they paid at least the minimum wage. That means keeping records of hours worked and pay, for 6 years. For technicians who travel between jobs, travel time between assignments usually counts as working time for minimum wage purposes, so it needs to be recorded too.
3. HMRC business records
HMRC requires records that support your tax return and VAT. Limited companies keep them for 6 years from the end of the financial year they relate to; sole traders and partnerships for at least 5 years after the 31 January Self Assessment deadline. Job sheets, timesheets, purchase invoices and sales invoices are part of that trail.
4. Daywork and time-and-materials contracts
On daywork or time-and-materials jobs, the client pays for the hours, materials and plant actually used. Signed daywork sheets are the basis for payment, and disputes usually come down to whose records are more complete. A digital work order workflow with photos and a signature on site settles that before it starts.
5. F-gas records
If you work on refrigeration, air-conditioning or heat pump equipment containing F-gases, you must record installation, maintenance, leak checks and refrigerant added or recovered, and keep those records for at least 5 years. This applies under both the UK F-gas regulations and the EU F-gas Regulation (EU) 2024/573.
6. Operating in the EU
In 2019 the Court of Justice of the European Union ruled that employers must have an objective, reliable and accessible system for recording each worker's daily working time. EU countries have implemented this in different ways, so check the local rules in every country where your teams work.
How long should you keep what? Overview (UK)
| What | Why | Keep for |
|---|---|---|
| Working time records | Working Time Regulations | 2 years |
| Hours and pay records | National Minimum Wage rules | 6 years |
| Job sheets, invoices, purchase records | HMRC (company / sole trader) | 6 years / at least 5 years after the filing deadline |
| F-gas equipment records | UK and EU F-gas regulations | At least 5 years |
Where record-keeping goes wrong in practice
The rules are rarely the problem. The problem is that hours and materials are recorded after the fact. The technician fills in a timesheet on Friday from memory, rounds down and forgets the travel time. Delivery notes go missing, so materials never reach the invoice or the job file. And the office retypes everything into accounting, adding new errors.
Records like that are weak in an inspection and cost you revenue on top: forgotten hours and materials are never invoiced.
How to meet record-keeping rules without extra paperwork
The fix is simple: record hours and materials at the moment the work happens, in the same place as the job. With OutSmart it works like this:
- Timestamped hours: the technician starts a timer on the work order, chooses work or travel time and stops at the end. Start, end and duration are stored; breaks can be recorded separately.
- Materials per job: items used go straight onto the work order from your own item list.
- Photos and signature: proof of the work and customer sign-off on site. You can make both mandatory before a work order can be sent.
- Review and export: with Timesheets you review hours per employee per week, approve or reject them and export to Excel.
- Straight to accounting: integrations pass hours and materials to the invoice without retyping.
Paper records vs. OutSmart
What changes when you record hours and materials digitally.
| Process step | On paper or in Excel | With OutSmart |
|---|---|---|
| Recording hours | From memory afterwards, rounded, no travel time | Timer on the work order with start, end and work or travel time |
| Recording materials | Delivery notes that get lost or never invoiced | Items on the work order, available for invoice and job file |
| Evidence in a dispute or inspection | Your word against theirs, or searching through folders | Photos, signature and timestamps per job, exported in minutes |
| Processing in the office | Retyping everything into accounting | Hours and materials flow to invoicing through the integration |
Get your records in order in 3 steps
Step 1: Work out which rules apply to you. Do you employ staff, work on daywork contracts, operate in the EU or work with F-gases? List per rule what you record and how long you keep it. Use the table above as a starting point.
Step 2: Record hours and materials on the work order, not afterwards. Have technicians record while they work, with timestamps, materials, photos and a signature. Make required fields mandatory so no work order comes back incomplete.
Step 3: Review weekly and connect your accounting. Approve hours once a week, export what your accountant needs and let invoices come from the integration. That way your records are inspection-ready every week, not just at year end.
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