A time risk allowance in NEC4 is time the Contractor adds to its plan for risks it carries, so operations can absorb them without affecting later work. Clause 31.2 requires each programme submitted for acceptance to show provisions for these allowances. A programme with none visible can be rejected for missing required information.
The term isn't defined in the contract, but the requirement is in both NEC3 and NEC4 ECC. Treat it as the Contractor's own time. It is part of how long the Contractor plans to take, not spare time available to anyone else. For how it sits with the rest of the plan, see the NEC programme guide.
Time risk allowance and float compared
| Time risk allowance | Float | |
|---|---|---|
| What it is | Time included in the plan for a known kind of risk | Spare time left once the planned durations and logic are fixed |
| Where it sits | Inside or alongside an operation | Between operations, or between planned Completion and the Completion Date |
| Why it exists | To make the plan realistic | A result of the sequence and dates |
| Effect of a compensation event | Remains part of the operation's planned time | See the NEC float guide |
Keeping them apart matters. If a Contractor has simply padded activities with no explanation, a reviewer can't tell allowance from float. And if a compensation event arrives, the Project Manager may then argue the padding is spare.
Three ways to show it
| Method | How it works | Trade-off |
|---|---|---|
| Separate activity | "TRA: Piling, 3 days" follows the operation | Clear and easy to check, but adds lines |
| Split in the duration column | A custom field shows 15 days' work + 3 days' allowance | Keeps the programme tidy, but viewers need the field |
| Stated in a narrative or schedule | A table against each activity or group | Good for a summary, but only works if it is kept up to date |
The contract doesn't prescribe a method, so check the Scope: NEC4 says the programme takes the form it states, and it may lay down the method. Whichever method you use, keep it consistent between revisions.
Sizing it
A flat percentage is easy, but often looks exactly like what it is. Better to think about each main operation: what risks you carry, how likely they are and how long they would take to overcome. The sizes below are for a fictional river wall and are purely illustrative:
| Operation | Planned work | Carried risk | Allowance |
|---|---|---|---|
| Sheet piling | 20 days | Plant breakdown, ordinary obstructions the Contractor could have allowed for | 3 days |
| In-situ capping beam | 15 days | Weather that falls short of the compensation event threshold, rework | 2 days |
| Commissioning | 5 days | Failed first test requiring a repeat | 2 days |
Don't include allowances for events that would be compensation events; those are dealt with through the contract's own mechanism. And bear in mind the Project Manager can test whether the programme represents your plans realistically, so being able to explain your allowances helps.
Risk allowances in compensation events
A separate rule applies when a compensation event is assessed. NEC4 63.8 and NEC3 63.6 say the assessment includes risk allowances for cost and for time, covering matters with a significant chance of happening that aren't compensation events (NEC3 frames these as matters at the Contractor's risk). So if a variation adds a new operation, its planned duration can include an allowance of its own, even if the extra time is hard to put a precise figure on.
In a quotation, show the allowance alongside the base duration and say what it covers. If you bury it, you are more likely to see it stripped out as unexplained. For how the rest of the time assessment works, see using the programme to assess compensation events.
What people get wrong
- Treating it as optional. Clause 31.2 lists it, so a programme can be rejected for omitting it.
- Assuming the Project Manager can reduce it at will. It is part of the Contractor's plan. The Project Manager's test is whether the plan is practicable and realistic, not whether the allowance is to its liking.
- Using up allowances without reflecting them. As work proceeds, record whether the allowance was used. Otherwise each revision carries assumptions that are out of date, and the progress the programme shows may not be accurate. Clause 32 asks for actual progress and its effect.
Related guides
- The NEC Programme: A Complete Guide
- Who Owns Float in NEC?
- Completion Date and Planned Completion
- What Counts as Completion?
- How Often to Revise the Programme
- Terminal Float in NEC
See how this works in practice
Click through Contract Status with sample contracts: raise the notice, reply to it, and watch both sides of one record.
Take the guided tour Book a demo
Try the planner role-play, use the free NEC tools or download free NEC templates.
This guide is general information in our own words, not legal advice. Your contract and its Contract Data always govern. NEC, NEC3 and NEC4 are trade marks of Thomas Telford Ltd; Contract Status is not affiliated with or endorsed by NEC.