CIS | Dartford
Commuting from Dartford to London Sites? The CIS Mileage Claim Most Subbies Never Make
Ask a Dartford subcontractor where they worked last year and you rarely get one answer. An Ebbsfleet phase in spring, a frame job in Canary Wharf through summer, snagging in Gravesend before Christmas. The DA postcodes are home to thousands of trades whose real workplace is the M25, the A2 and the Dart Charge gantry. And that commute is exactly where most of them leave their biggest tax deduction unclaimed. This guide explains how travel really works for CIS subcontractors, with Dartford numbers.
The rule that surprises everyone
Employees cannot claim the cost of getting to work. Self-employed CIS subcontractors usually can. The difference is the nature of the workplace: an employee has a permanent workplace, while a self-employed subbie moving from site to site has a series of temporary workplaces, and travel from home to a temporary workplace is generally an allowable business expense.
For a Dartford subbie, that means the daily run to Ebbsfleet, the months commuting to a London frame job, the trips between sites and the merchants: business miles, nearly all of it.
What the miles are actually worth
HMRC's simplified mileage rates are 45p per mile for the first 10,000 business miles each tax year and 25p per mile after that. (The alternative is claiming actual van costs plus capital allowances; we calculate both and use whichever is better for you.)
The Dartford-to-London year
Steel fixer, Dartford to a Canary Wharf job, roughly 19 miles each way, 4.5 days a week, 46 working weeks: about 7,900 miles. Add site moves, the merchants and a stretch at Ebbsfleet: 11,500 business miles for the year. Claim: (10,000 × 45p) + (1,500 × 25p) = £4,875. At the basic rate that is roughly £975 off the tax bill, before Dart Charge, parking and tolls are added. That is the average accountancy fee several times over, from one expense category.
Dart Charge, tolls and parking
The crossing charges stack up quietly: a subbie crossing the river daily spends hundreds a year on Dart Charge alone. Business-journey crossings, the Blackwall/Silvertown charges, congestion charge where it applies, and site parking are all claimable on top of mileage. Set your Dart Charge account to email receipts and the record keeps itself.
The records HMRC expects
- A mileage log. Date, from, to, miles, job. A phone app or a notebook in the van both work. Reconstructing a year from memory is possible (we do it from site records and bank statements) but contemporaneous logs are stronger.
- Crossing and parking receipts, or the statements from your Dart Charge and parking apps.
- Your payment and deduction statements from each contractor, which anchor where you actually worked.
Starting on the Lower Thames Crossing works or an Ebbsfleet phase? Start the mileage log on day one. A long infrastructure engagement can put £4,000 to £6,000 of travel deductions on a single year's return.
The limits: when travel is NOT claimable
Honesty matters here, because HMRC does check. If you work at the same single location for years on end with no expectation of moving, it can be treated as a permanent workplace, and home-to-site travel stops being allowable. Equally, personal journeys, detours and the school run share of a trip are out. The test is genuine business travel between home and genuinely temporary sites. Most multi-site CIS patterns pass it comfortably; a one-site-for-five-years pattern may not. We assess each case honestly before claiming.
Turning the miles into money
Travel is one line on the return. Tools, PPE, CSCS and plant tickets, materials, phone and insurance all stack on top, and the CIS tax already deducted from your pay is credited against the final bill, which is why most Dartford subbies are due a refund of £1,500 to £5,500 once everything is claimed properly. Get a 60-second estimate with the free CIS refund calculator, read the full refund guide, or see what we do locally: CIS accountant in Dartford.
Frequently Asked Questions
I never kept a mileage log. Can I still claim for last year?
Usually yes. We reconstruct mileage from your payment statements (which show who you worked for and when), site addresses, bank fuel transactions and Dart Charge records. The claim must be honest and defensible, not perfect. Then we set up a simple log going forward.
My van is also the family car at weekends. Does that stop me claiming?
No, it just means you claim the business share. The mileage method handles this neatly: you claim the business miles you log and the private use is simply not claimed.
Is it better to claim mileage or actual van costs?
It depends on the van, the miles and the costs. High-mileage drivers in cheap vans usually win with the 45p rate; expensive vans with finance and big repair bills can do better on actual costs. Once you pick a method for a vehicle you generally stick with it, so it is worth getting the choice right in year one. We run both numbers for every client.
Can I claim the Dartford Crossing for every trip?
For business journeys, yes. Crossings on personal trips are not claimable. Your Dart Charge statement plus the mileage log makes separating them straightforward.
I sometimes get a lift in another subbie's van. Can either of us claim?
Only the person whose vehicle it is claims the mileage or running costs. If you contribute fuel money to the driver, keep a record: a fair contribution to a genuine business journey can be claimable as your own travel expense. What you cannot do is both claim the same miles.
Do train or bus fares count when I leave the van at home?
Yes. Public transport fares for business journeys to temporary sites are allowable, alongside van mileage for the days you drive. Keep the contactless or railcard statement; a highlighted bank statement works fine as evidence.
What about hotel and food costs when a job is too far for the daily commute?
If you work away and stay over for business, reasonable accommodation costs and subsistence on those trips are generally allowable. The rules are tighter for food than people expect (everyday lunches near a regular site are usually not claimable), so keep the receipts and let us judge each pattern honestly.
Could claiming big mileage trigger an HMRC check?
Large round numbers with no records can. A well-evidenced claim does not need to be feared: log, statements and consistent figures mean that even if HMRC asks, the answer takes ten minutes. This is exactly why we build the evidence file with every return rather than just typing a number in a box.
Doing Dartford-to-London miles with nothing to show for it?
A 15-minute call tells you what your travel is worth and what refund you should expect. Fixed fees, same-day filing from 6 April.
Or email info@yourtaxhelp.co.uk | CIS accountant in Dartford
General guidance only. Not personal tax advice. Contact us for advice specific to your situation. Figures relate to the 2025/26 tax year unless otherwise stated.