An illustrative 60-tonne-a-year engineering business applying a £100 shadow price would add £6,000 to its annual investment calculations, not its tax bill. That is the practical point of internal carbon pricing: how to set a shadow price that changes decisions without pretending your company already faces a formal carbon charge.
This example uses disclosed assumptions rather than real company data. The business, Northfield Engineering Ltd, has 420 tonnes of annual emissions, expects a 60-tonne reduction from a proposed equipment upgrade and is comparing a £180,000 gas-fired option with a £205,000 electric option. At £100 per tonne, the avoided carbon value is £6,000, reducing the electric option’s effective cost gap from £25,000 to £19,000.
A shadow price is an internal management figure. It isn’t the same as a UK ETS allowance, a carbon credit or a government levy. Used properly, it helps a finance director see the cost of high-emission choices before regulation, customer requirements or energy prices make those choices more expensive.
“Isn’t an internal carbon price just an arbitrary number?”
It can be. A round figure pulled from a sustainability presentation won’t survive its first budget meeting. A useful shadow price has a documented reason, a clear scope and an owner who reviews it at least annually.
There are three sensible ways to set the starting point:
- Policy price: use a relevant external carbon cost, such as the current or expected cost of UK ETS allowances where your operations are directly covered.
- Risk price: estimate the likely financial exposure from regulation, customer demands, carbon border measures, energy costs and supply-chain disruption.
- Target price: calculate what carbon would need to cost internally to make your emissions reduction pathway financially attractive.
Many UK SMEs start between £50 and £100 per tonne of carbon dioxide equivalent. Larger businesses with material international exposure may model several prices, such as £50, £100 and £200. The right answer depends on your decisions, not on finding one universally correct rate.
The caveat is simple: a shadow price is not evidence that your business has paid for its emissions. It is a decision-making assumption. Keep it separate from reported emissions, carbon credits and claims about being net zero.
“Which emissions should the shadow price cover?”
Start with emissions that your decisions can influence and measure with reasonable confidence. For most businesses, that means Scope 1 fuel use, Scope 2 purchased electricity and selected Scope 3 categories such as purchased goods, freight, business travel and waste.
Use the GHG Protocol Corporate Standard to define the organisational boundary and reporting categories. If your baseline is still developing, don’t wait for perfect Scope 3 data. Apply the price to reliable categories first, then expand the scope as supplier data improves.
For example, Northfield could apply its price to:
- 420 tonnes of measured Scope 1 and Scope 2 emissions;
- the 60 tonnes expected to be avoided by the equipment project;
- the embodied emissions of major machinery, once supplier data is available; and
- freight emissions where transport activity is already recorded.
The calculation is straightforward: emissions in tonnes multiplied by the internal price. For 420 tonnes at £100, the notional annual exposure is £42,000. For the proposed 60-tonne reduction, the decision value is £6,000.
Don’t force a weak estimate into a precise-looking spreadsheet. A poor Scope 3 estimate priced at £137 per tonne creates false confidence. Record the data source, calculation method, emission factor and confidence rating beside every material input.
“Should we use one price or several?”
Use one price when simplicity matters more than precision. Use several prices when a project lasts for years, has regulatory exposure or could be affected by international policy.
A practical model might contain three scenarios:
| Scenario | Shadow price | Best use | Northfield’s 60-tonne saving |
|---|---|---|---|
| Lower case | £50 per tonne | Near-term budgeting and screening | £3,000 |
| Planning case | £100 per tonne | Capital investment decisions | £6,000 |
| Higher case | £200 per tonne | Long-life assets and regulatory stress testing | £12,000 |
The planning case should be the figure used in ordinary business cases. The lower and higher cases show the board how sensitive the decision is. If a project only works at £200 per tonne, that fact belongs in the approval paper.
For external context, compare your assumptions with the UK ETS guidance, but don’t copy an allowance price blindly. The UK ETS applies to covered installations and aviation activities. It doesn’t automatically represent the future cost of every tonne emitted by a manufacturer, retailer or professional services firm.
The contrarian view is that a single price can be more useful than a sophisticated curve nobody understands. A transparent £100 assumption, reviewed each year, is usually better than a complex model that procurement and finance quietly ignore.
“How do we put a shadow price into real business decisions?”
Put it inside the existing approval process. A carbon price that lives in a sustainability dashboard will rarely influence a £500,000 capital decision.
Capital expenditure
Add a carbon line to investment appraisals. Calculate the emissions difference between options, multiply by the relevant price and show the result alongside purchase cost, maintenance, energy and residual value.
Northfield’s electric option costs £25,000 more upfront but avoids 60 tonnes each year. At £100 per tonne, the annual notional benefit is £6,000. Ignoring discounting, the carbon-adjusted payback on the premium falls to about 4.2 years rather than 5 years based only on the £12,000 annual energy saving assumption. The carbon value doesn’t create cash, so it should be shown separately rather than presented as a guaranteed return.
Procurement
Ask suppliers for product or service emissions where those emissions could affect cost, customer retention or future compliance. Use the price to compare bids, identify data gaps and prioritise supplier engagement. A supplier with a slightly higher purchase price may be preferable if its lower emissions reduce future exposure.
For practical supplier requests, see this supplier engagement letter for Scope 3 data. The letter should ask for boundaries, methods, reporting years and assurance, not just an unsupported carbon number.
Budgets and business plans
Apply the shadow price to forecast emissions, then show the result as a management risk indicator. For Northfield, a forecast increase from 420 to 500 tonnes would raise notional exposure from £42,000 to £50,000 at £100 per tonne. That £8,000 difference can support an energy-efficiency project or prompt a review of production plans.
Need help checking the baseline before setting the price? Speak with our carbon audit team about your numbers before the figure gets embedded in a budget.
The caveat is that carbon-adjusted costs must not be used to disguise weak economics. A project should still have a credible operational case, and emissions reductions should be tracked after approval.
“Does this replace SECR, UK ETS or net zero targets?”
No. Each serves a different purpose.
SECR is a reporting requirement for qualifying UK companies. The UK Government SECR guidance sets out who reports and what information is expected. A shadow price is an internal management tool and doesn’t satisfy that obligation.
UK ETS obligations apply to specific covered activities. A business outside the scheme may still face indirect costs through electricity, heat, freight or suppliers, but it shouldn’t describe a shadow price as a compliance payment.
Nor does a shadow price replace a science-aligned target. Targets define the emissions reductions you intend to achieve; the price helps test whether decisions support them. If you want a formal target, distinguish between an internally approved pathway and target validation through the Science Based Targets initiative.
Some companies also use an internal charge, where business units actually transfer money into a decarbonisation fund. That is more powerful but harder to govern. Start with a shadow price unless you have reliable data, executive sponsorship and a clear use for the money collected.
One warning: don’t count avoided internal carbon costs as offsets. Paying into an internal fund doesn’t remove a tonne from the atmosphere.
“How often should the price change?”
Review it annually and whenever a major assumption changes. The review should cover regulatory developments, energy costs, emissions performance, customer requirements and the types of investment being assessed.
A sensible governance note records:
- the price and currency basis;
- the emissions categories included;
- the external sources and internal assumptions used;
- the person responsible for approval;
- the review date; and
- the decision thresholds affected by the price.
Don’t increase the number every year simply to signal ambition. If the rate rises from £50 to £100, explain what changed. Otherwise, managers will treat it as a sustainability preference rather than a financial planning assumption.
A shadow price may also need to vary by project life. A five-year vehicle decision and a 25-year building decision don’t carry the same policy risk. Use the higher case for long-lived assets where today’s choice could lock in emissions for decades.
The quiet test is whether the number changes a decision. If it never affects a specification, supplier question, investment ranking or budget, it is reporting decoration. Change the process before changing the price.
“What does a sensible first-year process look like?”
Keep the first cycle manageable. Map your material emissions, choose a planning price, test it against three live decisions and document where the result changes the recommendation.
For a typical SME, the first-year process can be:
- Confirm the organisational boundary and baseline year.
- Separate measured emissions from estimates.
- Set lower, planning and higher price scenarios.
- Apply the planning price to capital expenditure and procurement templates.
- Report carbon-adjusted results to finance and the board.
- Review the assumptions after six or 12 months.
Pair this with a wider reduction plan, rather than relying on the price alone. A practical net zero roadmap template for a small business can help connect the shadow price to actions, owners and deadlines.
For Northfield, the first-year recommendation would be a £100 planning price, £50 and £200 sensitivity cases, and coverage of measured Scope 1 and Scope 2 emissions plus priority freight and machinery purchases. That is enough to test the method without pretending the company’s entire value chain is measured perfectly.
The best shadow price is not the highest one. It is the one your finance team understands, your directors approve and your project managers actually use.
“What should we do next?”
Set a provisional price this quarter and test it on one live investment. If it produces a different answer, improve the data and governance around it. If it changes nothing, find out whether the price is too low or the approval process is too weak.
Arrange a practical carbon pricing discussion if you want an independent review of the calculation, boundary and decision rules.
Frequently asked questions about shadow carbon pricing
What is a reasonable internal carbon price for a UK SME?
There is no mandatory UK SME rate. Many businesses use a starting range of £50 to £100 per tonne, then test a higher case for long-lived assets or regulatory exposure. The rate matters less than documenting why you chose it, which emissions it covers and when it will be reviewed.
Is a shadow price the same as buying carbon credits?
No. A shadow price is an internal calculation used to compare decisions. Buying a carbon credit is a separate transaction involving a claimed reduction or removal elsewhere. Paying an internal notional amount does not compensate for emissions and must not be described as an offset.
Should Scope 3 emissions be included?
Include material Scope 3 categories when the data is good enough to support a decision. Start with categories such as purchased goods, freight and business travel where your organisation has influence. Record estimates clearly, use confidence ratings and expand coverage as supplier information improves.
Can a shadow carbon price be used for SECR reporting?
It can support internal planning behind your SECR figures, but it does not replace SECR reporting. SECR requires qualifying companies to disclose specified energy and emissions information in their annual report. Keep the shadow price, reported emissions and any compliance costs as separate lines.
Frequently asked questions
What is a reasonable internal carbon price for a UK SME?
There is no mandatory UK SME rate. Many businesses use a starting range of £50 to £100 per tonne, then test a higher case for long-lived assets or regulatory exposure. The rate matters less than documenting why you chose it, which emissions it covers and when it will be reviewed.
Is a shadow price the same as buying carbon credits?
No. A shadow price is an internal calculation used to compare decisions. Buying a carbon credit is a separate transaction involving a claimed reduction or removal elsewhere. Paying an internal notional amount does not compensate for emissions and must not be described as an offset.
Should Scope 3 emissions be included?
Include material Scope 3 categories when the data is good enough to support a decision. Start with categories such as purchased goods, freight and business travel where your organisation has influence. Record estimates clearly, use confidence ratings and expand coverage as supplier information improves.
Can a shadow carbon price be used for SECR reporting?
It can support internal planning behind your SECR figures, but it does not replace SECR reporting. SECR requires qualifying companies to disclose specified energy and emissions information in their annual report. Keep the shadow price, reported emissions and any compliance costs as separate lines.
