A row of green and yellow branded electric MINI Cooper cars parked on a London street, representing a company EV fleet. — Source: Shutterstock

Key Insights

With over 1,970,000 fully electric cars on UK roads as of March 2026, HMRC-compliant EV mileage reimbursement is now a core fleet management requirement.
HMRC now sets two Advisory Electricity Rates: 7p per mile for home charging and 15p per mile for public charging, effective from 1 March 2026.
Any reimbursement above either AER requires documented evidence of actual electricity cost per mile, or the excess becomes taxable pay subject to National Insurance.
Manual spreadsheets cannot reliably split business and personal mileage across home, public, and workplace charging without creating compliance gaps.
Reimburse uses a structured, HMRC-aligned cost allocation methodology with a full audit trail, replacing estimation with verified, payroll-ready data.

There are now more than 1,970,000 fully electric cars on UK roads, according to Zapmap data for March 2026, and a significant proportion of those vehicles are company cars. That means HMRC-compliant EV mileage reimbursement is no longer a niche fleet concern - it is a front-line obligation for HR, payroll, and finance teams across the country.

The problem is that most reimbursement processes were designed for petrol and diesel fleets. Fuel cost per mile was predictable, receipts came from a single point of sale, and the arithmetic was straightforward.

EV business travel works differently, however. A driver might charge at home overnight, top up at a rapid public charger during a client visit, and plug in at a workplace unit the following morning. Each session carries a different cost per kWh. Each has a different HMRC treatment. And none of it arrives in a single, reconcilable file.

For fleet managers, this creates a compliance gap that spreadsheets alone cannot close. HMRC is clear: reimburse above the advisory rate without evidence, and the excess becomes taxable pay. That is the risk sitting inside every manual mileage process in 2026.

This guide explains what HMRC requires, where current manual processes fall short, and how Reimburse - The Charge Scheme's EV mileage reimbursement product - replaces estimation with an audit-ready, payroll-ready methodology.

The HMRC Position: What Fleet Managers Need to Know In 2026

From 1 March 2026, HMRC sets two separate Advisory Electricity Rates (AERs) for fully electric company cars. This split rate structure was introduced in September 2025, replacing the previous single flat rate, and the public charging figure has already increased once since its introduction.

The Current AER Rates

Home charging: 7p per mile
Public charging: 15p per mile (increased from 14p from 1 March 2026)

These rates function in the same way as advisory fuel rates for petrol and diesel vehicles. Reimburse employees at or below the relevant AER for each charging type, and there is no taxable benefit and no National Insurance liability.

At What Point Do You Need Evidence?

The complication arises when actual electricity costs exceed the advisory rate - which, for drivers who rely on rapid public chargers, is common. HMRC permits reimbursement above the AER, but only where the employer can demonstrate that the actual electricity cost per mile is higher.

Without that evidence, any payment above the advisory rate is treated as taxable earnings subject to Class 1 National Insurance. This is an explicit position in HMRC's guidance on advisory fuel rates, not a grey area.

The Apportionment Requirement

Where a driver charges at both home and public locations during the same period, business mileage must be split between the two AER rates according to where charging actually took place. The 7p home rate and the 15p public rate cannot be averaged or interchanged. For a fleet running dozens of drivers across different charging environments, that apportionment demands structured data, not manual estimation.

The practical consequence is that the HMRC mileage rates that once required relatively simple record-keeping now demand a methodology sophisticated enough to capture charging location, calculate cost per mile by source, and retain a complete audit trail.

Key Takeaways

HMRC sets 7p per mile for home charging and 15p for public, from March 2026
Reimbursements above the AER rate require documented evidence of actual costs
Without evidence, excess payments above the AER attract National Insurance liability
Mileage must be apportioned between charging locations, not averaged across both

Why Your Current Manual Process May Be A Compliance Risk

The pivot from ICE to electric fleets has happened faster than most reimbursement processes have adapted.

As mentioned earlier, there are now over 1,970,000 fully electric cars on UK roads - a figure that has grown substantially each year, driven in part by EV salary sacrifice schemes and fleet procurement decisions made ahead of the 2030 ZEV mandate. The reimbursement infrastructure serving those vehicles hasn’t been able to keep up.

Most manual EV mileage processes rely on a combination of driver self-reporting, receipt uploads, and spreadsheet-based reconciliation. Each stage introduces risk.

Where Manual Processes Break Down

Mileage splits are estimated, not evidenced. Drivers approximate how much charging happened at home versus in public, without access to verified session data.
Finance teams work from unverifiable figures. Reimbursements are calculated using numbers that cannot be traced back to actual charging records.
Apportionment errors are routine. A driver reimbursed at the public charging AER for mileage generated by home charging is being over-reimbursed. A driver reimbursed at the home rate for expensive rapid charging sessions is being under-reimbursed, with the shortfall becoming their personal tax liability.
Audit readiness is reactive, not built-in. Spreadsheets reconstructed from driver estimates and bank statements do not meet the evidential standard HMRC expects during a business mileage r eimbursement review.

For f leet mana gers responsible for dozens or hundreds of drivers, the cumulative compliance exposure across a year is material. If HMRC selects a fleet for review, the ability to produce a clear, source-attributed record for every reimbursement decision is the difference between a straightforward process and a protracted investigation.

Key Takeaways

Manual processes rely on driver estimates that cannot be verified against actual sessions
Incorrect apportionment between home and public charging creates over- or under-payment
Spreadsheet-based records do not meet HMRC's evidential standard for audit purposes
Compliance risk compounds across large fleets where individual errors scale quickly

The Audit Trail: Moving from Estimates to Evidence

The core requirement for HMRC-compliant EV mileage reimbursement is traceability. Evidence must be captured at the point of charging and retained in a form that is retrievable on request. It cannot be produced retrospectively from memory or approximation.

Reimburse addresses this through a structured cost-allocation methodology aligned with HMRC guidance.

How Reimburse’s Methodology Works

Drivers submit a monthly odometer reading alongside their actual public charging spend for the period.
Reimburse calculates the business-and-personal mileage split, applying the employer-configured home charging rate to home mileage.
Public charging costs are allocated using actual session spend, not an estimated average.
A complete, session-attributed record is produced for every driver, every month.

That record constitutes the audit trail. Every reimbursement figure in the payroll output is traceable to a specific mileage submission and a documented cost calculation. For HR teams who have previously relied on reconstructing records after the fact, the shift to structured, contemporaneous data is significant.

Handling the Split AER in Practice

For fleet managers dealing with the public charging apportionment requirement, Reimburse captures where charging occurred and calculates the cost per mile accordingly. Home and public mileage are allocated separately, at the appropriate rate, producing a reimbursement figure that reflects actual driver behaviour. That approach is how the split AER is intended to be applied.

Drivers who charge across multiple environments - home, public rapid chargers, workplace charge points - often find that manual tracking does not reflect the reality of how they use their vehicle. Structured allocation removes the burden of record-keeping from the driver. They submit a single monthly odometer reading; the methodology handles the rest.

Key Takeaways

HMRC requires evidence of actual cost per mile for above-AER reimbursements
Reimburse generates a session-attributed audit trail as part of normal monthly operation
Home and public charging are allocated separately, matching the split AER requirement
Drivers submit one odometer reading per month; the system handles cost allocation

Simplifying Finance and Payroll: One File, Zero Manual Reconciliation

For finance and payroll teams, the practical challenge of EV mileage reimbursement is integrating it into their existing workflow and team. A process that produces clean, HMRC-aligned figures is only useful if those figures feed into payroll without creating a secondary reconciliation task.

Reimburse produces a single monthly payroll-ready file. Every driver's reimbursement for the period - calculated across home, public, and workplace charging using actual costs and verified mileage - is consolidated into one output.

What Does The Monthly File Replace?

Manual data entry from individual driver submissions
Cross-referencing between multiple spreadsheet tabs
Translating driver-supplied figures into payroll-compatible formats
Chasing incomplete or inconsistent submissions at month-end

For finance and payroll teams, the monthly process reduces to a single upload step. At scale - a fleet of 50 drivers with varying charging environments, different monthly mileages, and a mix of home and public charging - that reduction in touchpoints is where compliance consistency is achieved.

Cost and Compatibility

Reimburse is included free for employers who implement The Charge Scheme. The product is cost-neutral, funded through the National Insurance savings that the salary sacrifice structure generates. For finance teams evaluating total EV benefit provision costs, there is no incremental line item.

For employers running hybrid or ICE vehicles alongside an EV fleet, Reimburse works alongside existing reimbursement models. The structured EV methodology sits within the same monthly payroll cycle as conventional mileage claims, producing a unified process rather than a parallel administrative track. That compatibility matters for fleets in transition, where some drivers have moved to EVs and others haven’t

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

Why Should Fleet Accuracy Be Considered A strategic Requirement

HMRC compliance in EV mileage reimbursement is often framed as an administrative concern. In practice, it is a strategic one. Two failure modes create risk for the business - and both stem from inaccurate data.

The Cost Of Getting It Wrong

Under-reimbursement means drivers absorb genuine business charging costs that the employer is legally able to cover tax-free. For employees relying on public rapid chargers at 15p per mile or above, the shortfall is real money. It undermines the financial case for going electric without a home charger and creates friction with the very people the EV benefit is designed to support.

Over-reimbursement creates a different problem. Where payments exceed the AER without adequate evidence, HMRC treats the excess as taxable earnings. That triggers a National Insurance liability, a potential P11D exposure, and a retrospective correction that consumes significant payroll and finance resources. Neither outcome is manageable at fleet scale without a process designed to prevent it from occurring in the first place.

Accuracy as a Fleet Management Principle

EV leasing will continue to grow as a proportion of new fleet registrations, and the volume of EV mileage claims processed each month will increase consistently over the coming years. A process that is adequate for 20 electric drivers today will not scale to 80 without structural change.

The move from manual estimation to structured allocation isn’t a response to HMRC pressure alone. It is a recognition that accurate, evidence-based reimbursement is what a well-run fleet operation looks like in 2026. Reimburse provides the methodology, the audit trail, and the payroll output to make that standard achievable without adding administrative burden to HR, finance, or the drivers themselves.

For employers who want to understand how the full charging reimbursement picture fits alongside the broader salary sacrifice benefit, the two products are designed to complement each other: The Charge Scheme covers employee charging costs through gross salary deduction, and Reimburse ensures business mileage is reimbursed accurately and compliantly on the employer side.

Key takeaways

Under-reimbursement creates driver dissatisfaction and undermines EV benefit take-up
Over-reimbursement above the AER without evidence triggers National Insurance liability
EV mileage claim volumes will increase as fleet electrification continues to scale
Structured allocation is how accurate, compliant reimbursement becomes operationally sustainable

Frequently Asked Questions About EV Business Mileage Reimbursement

Yes. HMRC permits reimbursement above the AER - 7p per mile for home charging and 15p per mile for public charging from 1 March 2026 - provided the employer can demonstrate that the actual electricity cost per mile exceeds the advisory rate. Where that evidence exists, the higher reimbursement is tax-free.
Where it does not, any amount paid above the AER is treated as taxable earnings and is subject to Class 1 National Insurance.
Maintaining session-level charging records is the practical requirement for any fleet reimbursing above the standard rates.
Reimburse generates a full audit trail as a standard output of the monthly reimbursement process. Every reimbursement figure is traceable to a specific driver submission, a documented mileage split, and a calculated cost per mile by charging type. If HMRC requests evidence of how reimbursement decisions were reached, that record is available without requiring any retrospective reconstruction.
The business mileage reimbursement process is designed so that audit readiness is a by-product of normal operation, not a separate task.
Reimburse is built for company car fleets - specifically, drivers reimbursed using the Advisory Electricity Rate for business mileage in employer-provided vehicles.
Grey fleet drivers using their own electric vehicles for business travel are reimbursed under HMRC's Approved Mileage Allowance Payments (AMAP) scheme at 45p per mile for the first 10,000 miles, rather than the AER, and Reimburse's structured AER methodology is designed for the company car context.
If your fleet includes both, speak with the team about how best to structure the process across vehicle types.
Drivers submit a monthly odometer reading and their actual public charging spend via Reimburse.
The system calculates the business and personal mileage split and allocates home and public charging costs accordingly, using the employer-configured home rate and actual public session spend.
Workplace charging is captured within the same monthly process. The driver isn’t required to manually categorise individual sessions - the structured methodology handles the allocation from the single monthly submission.
Yes. Reimburse allows employers to configure the home charging rate applied to each driver's calculation. This means you can reflect your organisation's specific circumstances - for example, if you have agreed a higher home charging contribution as part of your EV benefit offering - while the system maintains the structured allocation that produces an HMRC-compliant output.
Any rate set above the AER will require supporting evidence of actual cost to avoid a taxable benefit exposure, consistent with the standard HMRC position.
The monthly payroll-ready file produced by Reimburse consolidates each driver's reimbursement amount for the period, calculated across home, public, and workplace charging using verified mileage and actual cost data.
The file is structured for direct upload into payroll, removing the need for manual data entry or translation. For finance and payroll teams running large EV fleets, this single file replaces what would otherwise be a multi-source reconciliation task each month.
No. Reimburse is included free for employers who implement The Charge Scheme. The audit trail, structured allocation methodology, and payroll-ready file output are all part of the standard product - there is no additional cost for the compliance features specifically.
The product is funded through the National Insurance savings generated by the salary sacrifice structure, making it cost-neutral for the employer.
For organisations evaluating the total cost of EV benefit provision, Reimburse adds no incremental line item to the benefit stack.
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.

Make Your EV Mileage Process Work For Your Fleet

The split AER, the apportionment requirement, and the evidence threshold for above-rate reimbursements have collectively raised the bar for what HMRC-compliant EV mileage reimbursement looks like in 2026. Manual processes built for simpler fleet compositions are not equipped to meet that standard consistently, and the compliance exposure that results is not limited to edge cases - it sits within the ordinary monthly payroll cycle of any fleet that has not updated its methodology.

Reimburse provides the structure that manual processes can’t. A single monthly driver submission, a complete session-attributed audit trail, and a payroll-ready file that reflects actual costs rather than estimates. For fleet managers, HR leads, and finance teams carrying responsibility for this process, that is what accurate, scalable, and defensible EV mileage reimbursement looks like.

For employees on The Charge Scheme, the broader benefit is that their personal charging costs are already handled through salary sacrifice, saving 20–50% on every charge depending on their tax bracket. Reimburse completes the picture on the employer side, ensuring that business mileage is reimbursed correctly and that the full value of the EV benefit is delivered without compliance risk on either side of the payslip.