What it is
A contract sum analysis (often shortened to CSA, and sometimes called a schedule of values or a cost breakdown) splits your contract sum into lines that can be valued separately as the work progresses. Each monthly application then values the work against those lines.
It is agreed at the start of the job, usually from your tender breakdown, and it is the backbone of every valuation that follows.
Why it matters
- Faster applications: each month you only update the progress on each line.
- Fewer arguments: the main contractor's QS can check a line against what is on site, instead of debating a lump sum.
- Better cash flow: work that is finished can be valued in full, rather than averaged across a large line that is only partly done.
- Clearer variations: changes can be priced and valued against the lines they affect.
How much detail?
Too few lines and every valuation becomes a negotiation; too many and the monthly update becomes a chore. A good rule is to break the work down by area or floor, then by system or activity, with each line small enough that a percentage complete is easy to agree on site.
For an electrical package, for example:
| Ref | Description | Value |
|---|---|---|
| 1.01 | Preliminaries and site set-up | £12,000 |
| 2.01 | Ground floor: containment | £18,500 |
| 2.02 | Ground floor: small power first fix | £22,000 |
| 2.03 | Ground floor: lighting and controls | £31,000 |
| 3.01 | First floor: containment | £17,500 |
| 9.01 | Testing, commissioning and O&M manuals | £9,000 |
Tips for a good contract sum analysis
- Price preliminaries properly. Set-up, management and site costs should be a line of their own, ideally valued over time, so you are not funding them until the end.
- Do not front-load unrealistically. A QS will spot inflated early lines and may mark the whole application down. A fair breakdown builds trust.
- Separate testing, commissioning and handover documents. These come at the end and are often held back; a separate line makes clear what is outstanding.
- Keep materials and labour visible where the Construction Industry Scheme applies, so deductions are taken from the right amount.
- Make sure it adds up to the contract sum exactly, and agree it in writing before the first application.
When it needs changing
Keep the agreed contract sum analysis fixed and add changes as variations, rather than editing the original lines. That keeps a clear record of what was in the contract and what was added later. When you come to value it each month, our payment application checklist covers the rest of the application.
In Constructicore you can paste a contract sum analysis straight from Excel, and each application is built from it, with last month's percentages alongside so each update takes minutes. Main contractors can set the breakdown for a package and invite the subcontractor, so both sides value against the same lines. See how payment applications work in Constructicore.
Published 8 October 2026, updated 9 October 2026.