What will actually land in your bank on an invoice — with the materials split applied properly, the travel line shown for what it costs you, and the reverse charge taken into account.
The whole invoice — labour, materials and everything else.
Only materials you directly incurred. Materials the contractor bought and recharged to you do not reduce the deduction.
Plant hire costs come out of the deduction base.
This does NOT come out. Enter it and the tool will show you what the deduction on it is costing.
If in doubt, the reverse charge is the default absent a written end-user notification.
Illustrative figures on 2026/27 rates and simplified assumptions. This is information, not advice, and it is no substitute for a proper calculation on your practice's real numbers. Ask us for the accurate version — it's free.
We will send the figures exactly as they appear, so you have them when you are sitting with a contractor, your bookkeeper or the bank. We use your address for that and for the monthly trades money email, nothing else, and you can unsubscribe from the first one you get.
What this is doing
It is charged on the payment less the cost of materials you directly incurred, and less consumable stores, fuel other than fuel for travelling, plant hire, the cost of manufacture or prefabrication, and the VAT you have charged. That is why a materials-heavy invoice and a labour-only invoice of the same value produce very different amounts of cash.
Two things this tool exists to make visible.
Travel and subsistence stay inside the base. A mileage line or a night away has the full deduction taken off it. That is correct under CIS 340, so there is nothing to reclaim. It is still worth seeing the number, because a business that covers a wide patch is having 20% taken off something that was never profit.
Who bought the materials changes the answer. You must have directly incurred the cost. If the contractor buys the materials and recharges them to you, you have not directly incurred them and no reduction is due. The same £3,000 of materials therefore either reduces your deduction by £600 or does nothing at all, depending purely on whose account they went on. It is worth deciding before the job rather than after it.
If the reverse charge applies you add no VAT to the invoice at all, and the customer accounts for it. The VAT does not reach you at all: before March 2021 you would have held it for up to four months. Set the reverse charge question in the tool and you will see the difference in what actually lands.
If you are not sure whether it applies, the reverse charge checker walks the six conditions in the order they have to be answered.
These tools use sensible simplifications. A free CIS review gets you the accurate version — and usually two or three things worth fixing before your year end.