Separate the original agreement from the change
Look at the original quote. What was included, and what does the customer now want added or changed? Describe the difference in plain language. A photo or drawing can help show exactly what you mean.
Record four things
- What changes compared with the original job?
- What does the change cost, and which VAT treatment applies?
- What does it mean for the schedule or other work?
- Who approved this version, and when?
Discuss the consequences beforehand
Tell the customer in good time that a change will cost more. Ask for written or digital approval before starting. If the price isn’t fixed yet, agree how you’ll calculate it and when you’ll ask for further permission. A signature alone does not replace a clear explanation of the costs.
A practical example
During a renovation, the customer asks for two additional power sockets. You describe their locations, the wall chasing, materials and making good. State the additional price and any effect on the schedule. Once approved, carry out the work and reference the agreement on the invoice.
Keep the context too
Keep the request, price proposal, approval and any photos together. A timestamp and identifiable version make the agreement easier to trace. In a dispute, the outcome depends on the whole agreement and the circumstances; a digital record does not automatically guarantee that you will win.