CIS Calculator: Net to Gross
You know what you need in the bank. This works back to the labour figure your invoice has to show, with materials, VAT and the domestic reverse charge all in the sum. It divides — it does not add the percentage back on, which is the mistake that leaves sparks short on every job.
Why you cannot just add the percentage back on
This is the whole reason the page exists. A subbie who wants £1,000 of labour in hand, knowing the contractor takes 20%, adds 20% to £1,000 and invoices £1,200. The contractor deducts 20% of £1,200, which is £240, and pays over £960. Forty quid short — and it happens on every single job until somebody points it out.
The deduction is a percentage of the invoice figure, not of the take-home. What you receive is 80% of what you invoiced, so to reverse it you divide by 0.8 rather than multiplying by 1.2. £1,000 ÷ 0.8 = £1,250, and 20% of £1,250 is £250, leaving exactly £1,000. At the 30% rate the gap is much wider: adding 30% gives £1,300 and pays out £910, whereas dividing by 0.7 gives £1,428.57 and pays out the £1,000 you actually wanted. That is £128.57 a job.
labour = take-home ÷ (1 − CIS rate). To hit a total payment including materials and VAT: labour = (payment − materials × (1 + VAT)) ÷ (1 + VAT − CIS). The calculator above shows the divisor it used so you can check it on a scrap of paper.Example 1: "I want £1,000 for my labour"
The simplest case — labour only, and you are asking about the labour that reaches you after the deduction. Materials and VAT do not come into it, because neither is touched by CIS. Same target, both rates:
| Target labour after CIS | £1,000.00 |
|---|---|
| At 20% — £1,000.00 ÷ 0.8Invoice this much labour | £1,250.00 |
| CIS deducted at 20% | − £250.00 |
| You receive | £1,000.00 |
| At 30% — £1,000.00 ÷ 0.7Invoice this much labour | £1,428.57 |
| CIS deducted at 30% | − £428.57 |
| You receive | £1,000.00 |
Note how much further you have to push the price at 30% for the same result. If a contractor is deducting 30% because you are not verified, the fastest route to a healthier invoice is not raising your rate — it is registering under the scheme so the deduction drops to 20%.
Example 2: "I need £2,000 in the bank, and £500 of that is materials"
Harder, and far more common. You have £500 of materials to cover, you are VAT registered at the standard rate charging VAT normally, and the contractor is deducting at 30%. The materials are outside the scheme, so they and their VAT come off the target first; only the remainder gets grossed up.
| Target payment in the bank | £2,000.00 |
|---|---|
| Less materials plus their VAT — £500.00 × 1.2 | − £600.00 |
| Left to cover with labour | £1,400.00 |
| Divide by (1 + 0.20 VAT − 0.30 CIS) = 0.90The labour figure to invoice | £1,555.56 |
| Labour £1,555.56 + materials £500.00 | £2,055.56 |
| VAT at 20% (rounded per line) | £411.11 |
| Invoice total | £2,466.67 |
| Less CIS at 30% of £1,555.56 | − £466.67 |
| Contractor pays you | £2,000.00 |
Bang on target. Worth remembering that £411.11 of what lands is VAT you are holding for HMRC, and £466.67 of your labour is sitting with HMRC until you file — so £2,000 in the bank is not £2,000 of profit in either direction. If you want the calculator to answer "what actually stays with me?", switch the toggle to …for my labour instead.
Example 3: the same job under the reverse charge
Now say the domestic reverse charge applies: your customer is UK VAT registered, the payment is reported under CIS, the work is standard rated, and they have not given you written confirmation that they are an end user. You state the VAT on the invoice but do not collect it, so VAT drops out of what reaches your bank — and out of the sum. Target £1,800 in the bank, £300 of materials, CIS at 20%.
| Target payment in the bank | £1,800.00 |
|---|---|
| Less materials (no VAT collected) | − £300.00 |
| Left to cover with labour | £1,500.00 |
| Divide by (1 + 0 VAT − 0.20 CIS) = 0.80The labour figure to invoice | £1,875.00 |
| Invoice subtotal — £1,875.00 + £300.00 | £2,175.00 |
| VAT at 20% under the reverse chargeStated on the invoice, paid to HMRC by the contractor, never reaches you | £435.00 |
| Less CIS at 20% of £1,875.00 | − £375.00 |
| Contractor pays you | £1,800.00 |
The CIS deduction is identical to what it would have been without the reverse charge — the scheme only ever looks at labour. What changed is that £435 of VAT no longer passes through your account on the way to HMRC. If you were quietly using the VAT float as working capital between returns, that is the cash flow hole to plan around.
When to use this, and when not to
Working backwards earns its keep when a number is fixed for you. A materials bill you have already paid and need covering this month. A day rate you have agreed with a mate who is subbing off you. A van payment that has to clear on the 28th. In those cases the question genuinely is "what does the invoice have to say?", and this is the tool for it.
Where it goes wrong is when it becomes your pricing method. CIS is not a cost — it is your own tax, paid early, and you get it back through Self Assessment or, for a limited company, through payroll. Gross up every job as though the deduction were money burnt and you will be 25% dearer than the spark quoting the same work properly, and you will lose the job. Price the work on what it is worth, then use this page to check the cash flow lands where you need it.
The other honest limit: this cannot conjure money out of a job that does not have it. If the target payment is less than your materials cost, the calculator will tell you so rather than quietly returning a nonsense figure.
For the forward version — labour and materials in, deduction and payment out — use the main CIS calculator. The background on the scheme itself is in CIS deductions explained for electricians, and the reverse charge has its own guide in the domestic reverse charge for electricians.
Frequently asked questions
How do you work out CIS net to gross?
Divide, do not multiply. If the contractor deducts 20% of your labour, the labour you receive is 80% of the labour you invoiced — so to get back to the invoice figure you divide your target by 0.8. At 30% you divide by 0.7. To take home £1,000 of labour you must invoice £1,250 at the 20% rate, or £1,428.57 at 30%.
Why can't I just add 20% back on?
Because a percentage taken off and the same percentage added back on are not the same operation. £1,250 less 20% is £1,000, but £1,000 plus 20% is only £1,200 — and £1,200 less 20% is £960. Adding the rate back leaves you £40 short on every £1,000 at the 20% rate, and £128.57 short at 30%.
Does the net-to-gross figure include materials?
Only if you are working back from the whole payment. Materials are outside the scheme, so they pass through untouched — the calculator takes the materials (plus VAT on them, if you are charging VAT) off your target first, then grosses up only what is left. If you are working back from your labour take-home, materials do not enter the sum at all.
Does the reverse charge change the net-to-gross sum?
It changes the divisor, because it changes what actually reaches your bank. Under the domestic reverse charge you state the VAT on the invoice but do not collect it, so the VAT is not part of the payment you receive and drops out of the calculation. The CIS rate applied to your labour is unchanged.
Should I quote by working backwards from a day rate?
Use it as a sanity check, not a pricing method. Working backwards tells you what an invoice has to say for a specific figure to land in the bank, which is useful when you have a fixed cost to cover. But CIS is withheld tax you get back at the end of the year, not a cost of doing the job — pricing every job as though it were gone for good will make you dearer than the spark down the road.
Guidance, not tax advice
The rates and rules used here follow HMRC's published guidance on the Construction Industry Scheme and the VAT domestic reverse charge. Rules change and your own position may differ — check GOV.UK or an accountant before relying on a figure. SparkQuote is a quoting and invoicing tool, not a tax adviser.
Sources on GOV.UK
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