Commercial subcontractor variation management.
Variations are where commercial subcontractors lose or recover money. This guide explains the governed path from a site instruction to the final account — evidence, commercial basis, internal review, authorised submission, and application — so that every change captured on site is still provable months later.
The problem variations solve
Commercial subcontracting is not a single quote and a single invoice. Scope changes on site — additional areas, revised drawings, abortive work, access delays, missing free-issue materials. Each change has a cost and a commercial value. If the evidence is not captured on the day it happens, the commercial basis is not prepared, and the submission is not tracked, the variation becomes unrecoverable by the time the final account is negotiated.
A variation register is not a spreadsheet of amounts. It is a governed record linking evidence, commercial basis, approval state, age, and value — from the site instruction to the money in the account.
Evidence capture
A variation starts with evidence — a written instruction, a revised drawing, a customer email, missing free-issue materials, an additional area, a reattendance, or a site record. The date, the cause and the affected work are captured the day it happens, not reconstructed from memory weeks later.
- ✓Written instruction, revised drawing or site record logged on the day
- ✓Date, cause and affected scope captured as structured evidence
- ✓Photos, diary entries and labour records linked to the variation
- ✓Potential entitlement distinguished from an agreed variation
Commercial basis
The variation is valued against the project's rate book or agreed basis. Missing rates block approval instead of being guessed. The commercial basis is prepared, reviewed internally, and held against the adjusted contract value — including negative variations (omissions or descope) that reduce the contract sum.
- ✓Valued from your rate book — never invented or guessed
- ✓Missing rates flagged as RATE REQUIRED, blocking approval
- ✓Negative variations (omissions) tracked through the adjusted contract value
- ✓Stranded committed cost or abortive work from an omission remains separately recoverable
Internal review
The variation passes internal commercial review — scope completeness, pricing accuracy, margin protection, and risk. This is the same four-QS discipline applied to the original tender: scope, measurement, commercial risk, and independent challenge. AI review complete does not equal approved to issue.
- ✓Scope completeness and pricing accuracy checked
- ✓Margin and commercial risk reviewed against the contract terms
- ✓Independent challenge — not a rubber stamp
- ✓AI review complete does not equal approved to issue
Authorised submission
The variation is submitted to the client or contract administrator with its evidence attached. It is tracked as submitted, agreed, rejected, disputed, or part-agreed. Unagreed changes surface with their age in days — so a variation raised in March does not quietly disappear by November.
- ✓Submitted with evidence attached — not a bare claim
- ✓Status tracked: agreed, rejected, disputed, part-agreed
- ✓Unagreed variations surfaced with age in days
- ✓Approval or rejection recorded with reason and date
Application and final account
Agreed variations flow into the next application for payment with the cumulative maths already done. The variation raised on site becomes provable at final account — because the evidence, the commercial basis, the approval and the application are all in one record.
- ✓Agreed variations flow into the next valuation automatically
- ✓Cumulative application maths done — not rebuilt each month
- ✓Variation provable at final account — evidence, basis, approval in one record
- ✓Final account status tracks every variation to resolution
A1 OS runs the governed path.
A1 OS captures the evidence on site, values the variation from your rate book, routes it through internal review, tracks the submission and its status, and flows agreed variations into the next application for payment — all in one record per project. AI prepares the drafts; you approve them.