How to charge for materials on a UK trade invoice

The short answer

Charge for materials using an agreed selling price that covers buying, handling and risk, not just the merchant’s bill. Show materials and labour clearly enough for the customer to understand. Apply the correct VAT treatment if registered, keep purchase records, and agree deposits and customer-supplied parts before ordering.

*By Kamal Leadbitter, Founder. Last reviewed November 2026.*

What are you actually charging for when you supply materials?

A customer sees a tap, a length of pipe or a stack of blocks. Your business also has to choose it, check compatibility, order it, collect it, store it and get it to site. Those tasks take time even when the fitting itself is straightforward.

My advice is to price the whole responsibility, then explain it plainly. A materials selling price can cover purchasing effort and commercial risk as well as the physical goods. It should not become an unexplained extra added after a customer has accepted the job.

Decide whether procurement time sits in your labour allowance, a separate agreed charge or the materials price. Any of those can work. Charging for the same collection journey in all three places without making that clear is where an otherwise sensible quote becomes difficult to defend.

Start with a job costing sheet rather than the invoice screen. List quantities, buying prices, delivery, likely wastage and return restrictions. The customer invoice is the readable version of that calculation, not a substitute for doing it.

How do you calculate a sensible materials markup?

Use your actual buying cost as the starting point. For a VAT-registered business entitled to recover the purchase VAT, that will normally mean the recoverable-VAT-exclusive cost. If you cannot recover that VAT, include it in your cost calculation instead.

Then allow for costs not already recovered elsewhere:

• Time spent selecting, ordering and checking materials.
• Delivery charges and collection journeys.
• Storage, handling and protection on site.
• Expected wastage that is realistic for the work.
• The risk of damage, returns and supplier administration.
• A profit contribution that makes supplying worthwhile.

Markup and margin are different. Markup is profit expressed against cost; gross margin is profit expressed against selling price. Confusing them can leave the job earning less than you intended.

For an illustrative calculation only, suppose your relevant materials cost is £200. Adding a 25% markup produces a £250 selling price before any applicable VAT. The £50 difference is a 20% gross margin, before you deduct the costs it must cover. These figures are arithmetic examples, not recommended market prices.

The formulas are simple: selling price equals cost multiplied by one plus the markup rate. For a target gross margin, selling price equals cost divided by one minus that margin. Use decimals in the calculation and check the result against your actual overheads.

A single percentage will not fit every order. A small specialist fitting can require more sourcing time than a large routine merchant delivery. Consider a clearly agreed procurement charge where a percentage would produce an unrealistic result, rather than quietly inflating quantities.

Should you separate materials and labour on the invoice?

Usually, a clear split helps builders and plumbers answer questions quickly. It also makes variations easier to trace. However, an agreed fixed-price job does not automatically need a public breakdown of every internal cost or your profit calculation.

Choose a level of detail that matches the quote. For a small repair, “replacement valve and associated fittings” may be clearer than several lines of washers and connectors. For a larger refurbishment, group materials by work stage or room so the customer can recognise what was supplied.

A practical layout might look like this:

Avoid writing “materials at cost” if you intend to add markup. That phrase can create a very different expectation from “materials supplied at the agreed selling price”. If the customer wants an open-book arrangement, agree the cost basis, markup and evidence before accepting it.

For fixed-price work, do not change the accepted price merely because your internal estimate was poor. Deal with genuine scope changes through an agreed variation, including the effect on labour, materials and completion timing.

How does VAT apply to materials on building and plumbing jobs?

Do not assume that separating materials from labour changes the VAT outcome. VAT depends on the supply and its circumstances, not simply on the invoice headings. HMRC’s construction guidance explains the treatment of building services and qualifying materials supplied with them. 6

For ordinary standard-rated domestic repairs supplied by a VAT-registered business, VAT is normally charged on the selling price, including the materials markup. It is not generally restricted to your profit or to the labour element. Certain construction supplies qualify for different treatment, so check the job rather than copying an old invoice.

Materials incorporated into qualifying work can have different treatment from goods sold separately, and some goods do not count as qualifying building materials. New-build work, conversions, energy-related work and business-to-business construction arrangements can need closer attention. Do not promise a reduced or zero rate without checking the conditions.

If you are not VAT registered, do not add a separate VAT charge to your customer invoice. Supplier VAT that you cannot reclaim still affects your costs, but that does not make your own invoice a VAT invoice. Explain the final payable total clearly.

Where registered, use accounting advice for unusual supplies or reverse-charge questions. A customer saying “the materials are already taxed” does not remove your obligation to apply the correct treatment to your own supply. Purchase VAT and sales VAT are separate parts of the calculation.

Which receipts and records should you keep?

Keep purchase invoices and receipts linked to the job, along with credits, delivery notes and the customer’s accepted quote. A photograph of a receipt taken promptly is more useful than a faded slip found months later, but make sure all the important details remain readable.

For VAT purposes, HMRC requires records of purchases and sales, copies of invoices issued and invoices received, among other records. Its guidance also explains digital-record requirements. Use that guidance to set your process rather than treating a bank payment alone as complete evidence. 4

Record what happened to unused items. Were they returned for a credit, retained as business stock or left with the customer under the agreement? An open-book arrangement should explain how supplier credits and discounts affect the bill. A fixed-price arrangement should still have accurate internal records.

A useful weekly routine is to match each merchant transaction to a job reference, check returns and flag missing invoices. That makes it easier to review whether your markup is covering real costs rather than simply looking healthy on paper.

What should you agree about customer-supplied parts?

Customer-supplied materials change the job, but they do not make planning unnecessary. Before booking, ask for the manufacturer, model, specification and delivery date. Check suitability before committing to an installation price where possible.

Explain who is responsible for ordering the right item, checking delivery damage and dealing with the retailer. Set out what happens if a part is missing, incompatible or late. Any additional visit or waiting-time charge should be described and agreed, not invented when the problem arrives.

You can distinguish your workmanship responsibility from responsibility for a product you did not sell. Do not use a sweeping “no responsibility whatsoever” statement as though it removes duties concerning your own work. Get appropriate advice on terms if you regularly fit customer-supplied goods.

If you cannot safely or properly fit the item, say so and pause. Offering a suitable alternative is better than installing something unsuitable simply because the customer has already paid for it. Keep a written record of the decision and any revised scope.

When should you ask for a materials deposit?

Ask when you have a genuine upfront commitment that the agreed payment plan needs to cover. A special order, a large delivery or a supplier requiring payment before dispatch can justify discussing an advance payment. The amount should follow that commitment, not an arbitrary habit.

Show the deposit as part of the job total, describe what it funds and state when the balance becomes due. Confirm receipt after payment and credit it against the final account. A deposit is not an extra materials charge on top of the price already accepted.

VAT-registered businesses should check the timing carefully. HMRC says the tax point for an advance payment is the earlier of issuing a VAT invoice for it or receiving it. Do not automatically postpone all VAT until completion. 3

Cancellation and refund terms need separate attention, especially for consumers agreeing work at home or remotely. Do not assume that buying materials makes every deposit non-refundable. Before ordering bespoke items or starting early, check the applicable cancellation rules and have appropriate terms in place.

What final checks prevent a materials invoice dispute?

Read the invoice alongside the accepted quote. The descriptions, quantities and pricing basis should tell the same story. Check that supplier returns, approved extras and previous payments have not been missed. Confirm that the customer can see the amount still due without doing their own calculation.

Before sending, ask yourself three questions: could a customer identify the work, could you explain the materials price, and could you trace the supporting records? If any answer is no, fix the document first. Clear paperwork is cheaper than a long argument about what “materials included” was supposed to mean.

Frequently asked questions

Can a builder or plumber add markup to materials?

Yes, agree a selling price that covers your supply costs and profit. Make the pricing basis clear before acceptance, particularly if the customer expects materials at cost. There is no single markup that makes commercial sense for every business or every order.

Do I have to show my merchant receipt to the customer?

For an ordinary agreed-price job, your customer invoice and your buying records serve different purposes. If you promise open-book pricing or reimbursement at cost, agree what evidence you will provide. Keep purchase records regardless of whether copies go to the customer.

Is markup the same as a handling charge?

Not necessarily. Markup is built into the selling price, while a handling charge is a separately described amount. Either approach should fit the agreed quote. Avoid charging twice for the same activity without explaining the arrangement to the customer beforehand.

Do I charge VAT only on my materials profit?

For a normal standard-rated supply, a VAT-registered business generally accounts for VAT on the selling price, not just the markup. Construction exceptions and other arrangements can change the treatment. Check HMRC’s guidance for the actual supply rather than guessing from the supplier receipt.

How do I show a materials deposit on the final invoice?

Show the full agreed job value, identify the advance payment already invoiced or received, and show the balance left to pay. Reconcile VAT with earlier documents where relevant so the deposit and its VAT are not counted twice.

What should you do next?

Make the scope, payment stages and balance easy to understand before work starts. Try SaidToPaid free and use the free sector resource pack to put a clearer quoting and invoicing routine in place.

Sources and photograph

• HMRC: buildings and construction VAT
• HMRC: keeping VAT records
• HMRC: VAT on deposits
• GOV.UK: doorstep selling rules

Illustrative photograph by Max Payload on Unsplash, not a SaidToPaid customer case study.