An NEC4 subcontract isn't a mirror of the main contract, and that's deliberate. The ECS uses the same clause numbers as the ECC but different periods, so that the Contractor has time to pass notices up and replies down. Getting them to work together means understanding those differences.
This page uses the unamended NEC4 ECC and ECS. Amendments often change these figures, so check yours. For the form itself, read the guide to the ECS, and for the other forms, see NEC contract types.
How the periods align
| Step | Clause | ECC | ECS | Effect on the Contractor |
|---|---|---|---|---|
| Notify a compensation event | 61.3 | 8 weeks | 7 weeks | A one-week window to notify upwards |
| Reply to the notification | 61.4 | 1 week | 2 weeks | Time to get the Project Manager's view first |
| Submit a quotation | 62.3 | 3 weeks | 2 weeks | One week to review and include it |
| Reply to a quotation | 62.3 | 2 weeks | 4 weeks | Time to reply after the Project Manager has |
| Revised quotation | 62.4 | 3 weeks | 2 weeks | One week again |
| Further wait before treated acceptance of a quotation | 62.6 | 2 weeks | 3 weeks | An extra week below |
| Reply to a programme | 31.3 | 2 weeks | 3 weeks | Time to check it against the main programme |
| Further wait before treated acceptance of a programme | 31.3 | 1 week | 2 weeks | An extra week below |
| Payment after the assessment date | 51.2 | 3 weeks | 4 weeks | Money comes in before it goes out |
A worked timeline
Suppose a Project Manager instructs a change affecting a fictional steelwork subcontract. The Project Manager instructs the Contractor to quote, and the Contractor instructs the Subcontractor at once.
| End of week | Event | Contract |
|---|---|---|
| 0 | Instructions to quote issued at both levels | Both |
| 2 | Subcontractor's quotation due | ECS 62.3 |
| 3 | Contractor's quotation due, including the subcontract's cost and its own | ECC 62.3 |
| 5 | Project Manager's reply due | ECC 62.3 |
| 6 | Contractor's reply to the Subcontractor due | ECS 62.3 |
That leaves one week to digest the subcontract quotation and one week to pass down the decision. It's workable only if the Contractor stays alert: a slip in the first week uses up the whole margin.
Where "back-to-back" breaks down
- The events differ. A subcontract event doesn't automatically match a main contract one. Something that delays the Subcontractor might be the Contractor's own co-ordination failure, which has no route up to the Client.
- The test may differ. Each contract's physical conditions or weather event depends on what its own data and knowledge say. Compare the weather data entries in each document. A subcontract could use a different location or measure.
- The main Option may differ. A package on Option A under a Contractor on Option C gives different money flows. A quotation at subcontract level is the Subcontractor's price. Upstream, it feeds a target.
- Dates may not line up. Key Dates and the Subcontract Completion Date should leave space for the Contractor's later work. A week's delay below won't necessarily mean a week's delay above.
- Amendments can undo the alignment. A Z clause that shortens the main contract's time for notifying events could leave the Contractor with less time than its subcontract gives. Whenever you change a period on one level, check the other.
Early warnings and programme
Warnings need passing on too, since a subcontract warning doesn't reach the Project Manager by itself. That chain is covered in the early warning guide for subcontractors. For programmes, review a subcontract programme against the Accepted Programme before you accept it, because accepting one that doesn't fit could hand the Subcontractor an argument later.
Practical steps for a Contractor
- Set up a single table for each subcontract, showing both sets of periods. Don't rely on memory.
- Link every subcontract event to the main contract event if one exists. A register that records both references makes gaps obvious. See the compensation event register guide.
- When the Project Manager instructs a change, instruct affected Subcontractors the same day.
- Don't accept a subcontract quotation before you know the main contract outcome unless you are ready to carry the difference.
- Check that your subcontract data periods haven't been changed in a way that removes the Contractor's margin.
- Pass down the main contract requirements that affect the package, and do it in the Subcontract Scope, not in general wording.
Other subcontract forms
The same principle applies to the PSS, whose notification and quotation periods match the ECS's. The NEC4 ECSS differs: three weeks to notify an event (61.3) and one week to quote (61.2). For the TSS, read the figures from your own copy, since each form has its own.
Related guides
- NEC Contract Types: Which Form Do You Need?
- Task Orders Under NEC Term Service Contracts
- Professional Services Under NEC
- ECC vs TSC: Works or Term Service?
- ECC vs PSC: Works or Professional Services?
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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.