Why EVs Have Broken Business Mileage
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There are now more than 1,970,000 fully electric cars on UK roads. Fleet electrification is no longer a future planning exercise. It is the operational reality that finance directors, fleet managers, and payroll teams are managing at the moment.
The problem is that business mileage reimbursement has not kept up. The frameworks most businesses use were designed for a world of stable, predictable fuel prices. A petrol car uses petrol, of course. The price per litre varies within a relatively narrow band. An advisory fuel rate, reviewed quarterly, does a reasonable job of approximating cost.
Electric vehicles broke that model. A driver charging at home overnight might pay around 25p/kWh under the current Ofgem price cap. The same driver stopping at a motorway rapid charger on a business trip could pay 76p/kWh or more. The cost of the same journey can vary by a factor of three depending entirely on where the charge happens to take place. No flat rate can account for that without systematically over- or under-reimbursing someone.
Understanding how EVs have broken business mileage reimbursement - and why traditional fixed-rate models are no longer fit for purpose - is the first step toward fixing the problem. Reimburse, the modern fleet solution built by The Charge Scheme, combines actual charging data with configurable rates to produce accurate, HMRC-aligned electric car reimbursement for every driver, every month.
The Variable Cost Dilemma: Comparing Home and Rapid Charging Costs
The central challenge of EV business mileage reimbursement is variability. Petrol has a pump price. Electricity has a charging location. And the gap between locations is wide enough to break any fixed reimbursement model.
Home Charging: The Baseline
An employee charging their company EV at home pays around 24.67p/kWh under the current Ofgem price cap. At an average EV efficiency of roughly 3.5 miles per kWh, that translates to approximately 7p per mile in actual energy cost. This is why HMRC's home charging AER sits at 7p/mile. In this scenario, the variable charging costs are low and predictable, and the advisory rate is a reasonable approximation.
Public Rapid Charging: A Different Cost Environment
Now consider the same employee on a business trip. They pull into a motorway service station and connect to a rapid charger. According to the Zapmap Price Index, the weighted average PAYG cost for rapid and ultra-rapid charging (50kW and above) in March 2026 was 76p/kWh. At the same efficiency figure, that is approximately 22p per mile in actual energy cost, more than three times the home charging rate!
The range across networks illustrates just how extreme the variable charging costs can be:
The top ten rapid charging networks in March 2026 ranged between 57p/kWh and 89p/kWh
At the lower end, a driver pays around 16p/mile in actual energy cost
At the upper end, closer to 25p/mile
HMRC's public charging AER of 15p/mile falls short of the weighted network average
What HMRC's Split Rate Tells Us
HMRC introduced separate home and public HMRC mileage rates in September 2025. From 1 March 2026, home charging sits at 7p/mile and public charging at 15p/mile. By creating two rates, HMRC formally acknowledged that the variable charging costs between home and public environments are too significant to be captured by a single figure.
But even 15p/mile falls 30-50% short of what a driver actually spends at a rapid charger. The split rate is a step forward. It is not a complete solution.
For finance teams managing EV cost allocation across any meaningful fleet size, the compounding effect of this gap is significant. One driver doing 10,000 business miles per year with a substantial proportion on public rapid chargers could face an annual reimbursement shortfall running into hundreds of pounds.
Key Takeaways
Home charging costs around 7p/mile; rapid public charging averages roughly 22p/mile
Rapid charging ranged from 57p/kWh to 89p/kWh across the top UK networks in March 2026
HMRC introduced a split AER in September 2025: 7p/mile home, 15p/mile public
Even the public AER falls short of actual rapid charging costs by 30-50%
Why AER Under-Reimburses Your Best Drivers
The drivers most exposed to AER under-reimbursement are, almost without exception, the highest-mileage drivers doing the most important travel. Understanding this is central to the case for mileage claim accuracy as a strategic priority, not just an administrative one.
Who Bears the Shortfall?
A field sales manager covering 25,000 business EV charging miles a year isn’t doing those miles from their driveway. They’re travelling between clients, stopping at motorway service stations, and charging at whatever network is available at 76p/kWh or more. Reimbursing them at 15p/mile does not come close to covering their actual charging costs.
Let’s look at the numbers:
Actual energy cost at average rapid charging rate (76p/kWh): approximately 22p/mile
HMRC public charging AER: 15p/mile
Shortfall per mile: approximately 7p
Annual shortfall on 10,000 public charging miles: approximately £700
At 25,000 public charging miles, that shortfall approaches £1,750 per driver per year. Across a fleet of ten such drivers, the cumulative under-reimbursement exceeds £17,000 annually, absorbed directly by the employees doing the most work.
The Compliance Exposure
HMRC does allow employers to reimburse above the AER, provided they can demonstrate that actual charging costs per mile are higher. But demonstrating that requires evidence: receipts, charging session data, and a documented methodology. Most businesses running a company car fleet don’t have that infrastructure in place.
Without it, fleet managers face a choice between two unsatisfactory positions:
Reimburse at AER and under-pay drivers who charge publicly
Reimburse above AER without the evidence to support it, creating a tax exposure
Neither position supports mileage claim accuracy. Both are avoidable with structured cost allocation.
The Retention Risk
There is also a talent dimension. A driver who is consistently out of pocket on business travel (by hundreds or thousands of pounds per year) has a tangible financial grievance. For HR teams managing retention in a competitive market, under-reimbursement is not a minor administrative issue. It is a pay problem by another name.
Key Takeaways
Payroll integration is handled by The Charge Scheme's team, not your IT department.
The deduction structure follows standard salary sacrifice logic; no new payroll processes are required.
Employee data requirements are minimal; no individual financial data is needed at setup.
The full configuration can be completed in as little as two weeks from sign-off.
The Grey Fleet Money Leak
AER under-reimbursement is one side of the distortion problem. On the other side sits the grey fleet, and the issue there runs in the opposite direction. Reducing grey fleet costs in 2026 means understanding both sides of the equation.
What Does Grey Fleet Mean?
Grey fleet refers to employees using their own privately owned vehicles for business travel. Under HMRC's Approved Mileage Allowance Payment (AMAP) scheme, employers can reimburse private vehicle use at 45p/mile for the first 10,000 miles per year, then 25p/mile thereafter. For petrol or diesel cars, grey fleet AMAP is broadly reasonable. For privately owned EVs, the picture is different.
Where the Grey Fleet AMAP Overpayment Occurs
An employee driving their own electric car for business travel and claiming at 45p AMAP/mile is receiving a payment structured around ICE vehicle costs. That rate is designed to cover:
Fuel (actual EV energy cost: approximately 7p/mile at home, or up to 22p/mile publicly)
Wear and tear, insurance, and depreciation
The problem is that EVs have substantially lower running costs than petrol or diesel vehicles. Wear and tear is reduced. Fuel cost is lower. Yet the grey fleet AMAP rate is identical. For employees who charge predominantly at home, the fuel component of their claim may represent as little as 7p/mile, leaving 38p/mile covering non-fuel costs that may be materially lower for an EV than for a petrol car.
For fleet cost saving, the cumulative effect across a sizeable grey fleet is meaningful. An employer with 50 grey fleet EV drivers each doing 8,000 business miles per year at 45p/mile is paying out £180,000 annually in mileage allowances. If the actual cost profile of those journeys is substantially lower than the AMAP rate implies, the excess represents a direct and ongoing budget inefficiency.
The Grey Fleet Problem in Practice
Most businesses are aware that the grey fleet AMAP rate feels imprecise for EVs. Few have a structured way to address it. Reducing rates requires evidence of actual costs; applying a blanket reduction without that evidence creates its own compliance risk.
The hidden costs of personal EV charging are real for drivers. The hidden costs of imprecise grey fleet reimbursement are equally real for employers. The starting point for addressing both is the same: replacing flat-rate estimation with a structured methodology that reflects what charging actually costs.
Key Takeaways
Grey fleet AMAP pays EV drivers 45p/mile regardless of actual EV running costs
EV fuel costs are substantially lower than petrol equivalents, making AMAP potentially generous
Across a sizeable grey fleet, the cumulative budget impact of imprecise rates is significant
Replacing flat-rate estimation with structured cost data is the only reliable fix
Accuracy as a Strategic Priority
The financial distortions described above - AER under-reimbursement for company car drivers and AMAP overpayment for grey fleet EVs - aren’t edge cases. They’re structural features of applying fixed rates to a variable-cost fuel environment. Mileage claim accuracy is a financial and compliance requirement. The only way to achieve it is to replace estimation with actual-cost data.
What Does Structured Cost Allocation Look Like?
Reimburse replaces manual AER reconciliation with a structured EV cost allocation built around three inputs:
Actual public charging spend: the driver's real expenditure on public charging sessions during the month
Total miles driven: captured via monthly odometer submission, with no GPS or telematics required
Employer-set home charging rate: a configurable rate aligned to HMRC guidelines for EVs, applied to home-charged miles
From these three inputs, Reimburse calculates a proportional cost allocation and produces a payroll-ready electric car reimbursement figure. The methodology is documented and HMRC-aligned, with a full audit trail of all submissions and calculations available at any time.
Why Is Manual Reconciliation Not Scalable for 2026 Fleets?
Many finance teams currently handle EV mileage in spreadsheets. A small fleet can manage this, but the model breaks down quickly:
Each driver has a different charging mix (home, workplace, public, rapid, slow)
Public charging receipts vary by network, session, and date
No standard format exists across charge point operators
Reconciliation requires manual matching of charging data to journey records
The process repeats every month for every driver
For a fleet of 20 drivers, this is already a material admin burden. For 50 or 100, it becomes operationally unsustainable. The business mileage case for structured allocation grows directly with fleet size.
The Audit Trail Argument
Beyond admin efficiency, there is a compliance dimension.
HMRC permits reimbursement above AER where the employer can demonstrate that actual charging costs per mile are higher. Without a documented methodology and a retrievable audit trail, that demonstration is not possible. A finance team managing an EV fleet without structured records is carrying both administrative risk and tax risk.
For HR and fleet managers who have built reimbursement policies in good faith but without an evidence-based framework, structured cost allocation changes the compliance position significantly.
Key Takeaways
Structured cost allocation uses actual public charging spend plus a configurable home rate
No GPS or telematics is required - odometer submission is the only driver input
Manual spreadsheet reconciliation is not scalable for the 2026 fleet electrification levels
An HMRC-aligned audit trail is required to support above-AER reimbursement
The Cost-Neutral Finance Solution
One of the most common objections to implementing a new fleet management tool is cost. Reimburse addresses this directly: it is funded through NI efficiency within The Charge Scheme structure and carries no additional cost to the employer.
What Is The Monthly Process?
Each month, the process runs as follows:
Employees submit a single mileage reading through the app. This takes approximately 10 seconds and is the only action required of them.
The system calculates their total charging cost for the month, covering home, workplace, and public charging, based on the mileage data and recorded charging sessions.
The calculated deduction is provided to your payroll team as a single line item per employee, processed as a salary sacrifice deduction before tax.
Employees see the deduction on their payslip, alongside their existing car scheme deduction if applicable.
There's no manual reconciliation, no receipt collection, and no expense claim process. For HR teams currently managing business mileage reimbursement alongside their car benefit, the contrast in admin burden is significant.
Reporting And Visibility
HR and payroll teams have access to a centralised reporting dashboard.
The key outputs include:
Monthly deduction totals and employee-level usage data
Scheme participation rates and enrolment status
kWh charged and estimated CO2 displacement data, useful for sustainability and Net Zero reporting
Exportable reports in standard formats for payroll processing and internal benefit reviews
For organisations with Net Zero commitments, this data provides measurable evidence of progress rather than policy aspiration. Reporting on workplace green benefits, including kWh charged, CO2 displaced, and scheme participation rates, is increasingly expected as part of ESG and sustainability disclosures, and The Charge Scheme dashboard makes that straightforward.
It's also useful for finance and payroll teams who need clean, consistent records of salary sacrifice deductions across the workforce.
What Doesn't Change
Once the scheme is running, your payroll process remains the same. The Charge Scheme deduction follows the same payroll cycle as your existing salary sacrifice benefits, and the payroll automation that handles the monthly calculation means there are no additional sign-off requirements, no mid-month adjustments, and no manual exceptions to process in normal circumstances.
For HR and fleet managers who've been cautious about adding new benefits because of the ongoing admin commitment, this is the part of the implementation worth emphasising: once it's set up, it doesn't create new work.
Key Takeaways
Reimburse is cost-neutral: funded through NI efficiency savings via The Charge Scheme
No setup or running costs for businesses of any size
Employers receive a monthly payroll-ready file with a full HMRC-aligned audit trail
The reimbursement problem grows with fleet electrification - structured allocation scales with it
Frequently Asked Questions About EV Business Mileage Reimbursement
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HMRC permits employers to reimburse above the Advisory Electric Rate provided they can demonstrate that the actual electricity cost per mile is higher than the advisory rate.
From 1 March 2026, the AER is 7p/mile for home charging and 15p/mile for public charging. Where a driver uses rapid chargers that cost more per mile than 15p, a higher rate of electric car reimbursement is permissible - but only with supporting evidence of actual cost. Without a documented methodology and retrievable records, HMRC mileage rates above AER cannot be safely applied.
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This is precisely how EVs have broken business mileage reimbursement: traditional advisory fuel rates work because petrol and diesel prices move within a predictable range. Variable charging costs for EVs do not behave the same way.
Home charging costs around 25p/kWh under the current Ofgem cap; rapid public charging averaged 76p/kWh across UK networks in March 2026, per the Zapmap Price Index. That is a threefold difference in actual charging costs between locations. A single flat rate cannot represent both scenarios accurately, resulting in systematic under-reimbursement for public network users and potential overpayment for home-only chargers.
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Manual EV mileage reconciliation requires finance teams to collect receipts from multiple charge point operators, match session data to journey records, apply different rates for home and public charging, and produce a reimbursement figure for every driver, every month.
Each network issues receipts in a different format. Business mileage tracking across mixed home, workplace, and public sessions creates a volume of inputs that spreadsheet processes cannot handle efficiently at scale. As fleet electrification 2026 accelerates, the admin burden compounds with every additional EV driver.
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Yes. Reimburse is designed specifically for EV cost allocation but operates alongside existing reimbursement models for petrol, diesel, and hybrid vehicles.
There is no requirement to overhaul existing fleet operations or mileage policies. The platform handles EV drivers within the same payroll cycle as ICE vehicle claims, producing a single consolidated output.
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When employees pay for personal EV charging through The Charge Scheme's salary sacrifice charging arrangement, their gross salary is reduced. Lower gross salary means lower employer National Insurance contributions.
The NI efficiency generated by that structure funds Reimburse, making the platform cost-neutral for the employer. There are no setup fees and no ongoing running costs.
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Public EV charging is subject to 20% VAT, while domestic electricity used for home charging attracts only 5% VAT. This means every unit of electricity charged publicly costs the driver more in tax than the equivalent unit charged at home - a structural inequity that compounds the variable charging costs between locations.
For drivers relying heavily on the public charge point network, the VAT disparity adds a further layer of actual charging costs that flat-rate AER does not account for.
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No. Reimburse. requires no GPS, telematics, or tracking hardware. Mileage is captured through a monthly odometer submission by each driver.
The platform combines that total mileage figure with actual public charging spend and a configurable home charging rate to calculate a proportional cost allocation for the business reimbursement. The absence of hardware is deliberate: it removes the cost and complexity of device installation while maintaining an HMRC-aligned EV mileage reimbursement methodology that supports mileage claim accuracy without surveillance.
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Flat-rate reimbursement applies the same pence-per-mile figure regardless of how or where a driver charged. A driver whose actual charging costs were around 7p/mile at home receives the same reimbursement as a driver who paid 22p/mile at a rapid motorway charger. The first driver is reimbursed fairly. The second is under-reimbursed by approximately 7p/mile.
Across a fleet with mixed charging behaviour, the aggregate distortion creates both budget inefficiency and employee relations risk. Replacing AER with accurate reimbursement through structured cost allocation is the only way to eliminate the distortion entirely.
Fix EV Mileage Reimbursement Before It Becomes a Bigger Problem
Fleet electrification is not slowing down. With over 1,970,000 fully electric cars now on UK roads and company car BiK rates remaining among the lowest in the market, the proportion of EV drivers in any given fleet will continue to grow through 2026 and beyond.
Every quarter that passes with flat-rate AER in place is another quarter of under-reimbursed drivers, imprecise grey fleet AMAP payments, and unaudited mileage claims. For finance teams and HR teams who want to get ahead of the problem rather than manage it reactively, the case for structured EV cost allocation is straightforward.
Reimburse delivers HMRC-aligned electric car reimbursement with no setup cost, no telematics hardware, and no manual reconciliation. One monthly odometer submission per driver. One payroll-ready file per month. A full audit trail, always available.
For employers already running The Charge Scheme, Reimburse is included as part of the same implementation. For those who are not yet signed up, find out how The Charge Scheme works for employers or explore the Reimburse platform in more detail.
Last updated: 31/03/2026
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