Every tradesperson has had this moment: the job's finished, the invoice is sent, and somehow the profit isn't there. Not because the quote was wrong on labour or materials — but because a string of small, easy-to-forget costs quietly ate into it. None of them are big on their own. Add them up across a year of jobs, and they're often the entire difference between a profitable business and one that just about survives.
It's rarely one big mistake that destroys your profit. It's usually twenty or thirty small costs that were never included in the quote.
Here are 25 of the most commonly forgotten costs, grouped by where they usually hide.
Waste & Site Costs
1. Skip hire
Skip prices vary a lot by region, so here's a direct comparison — Swansea/South Wales pricing against London, as of July 2026:
| Skip Size | Swansea / South Wales | London |
|---|---|---|
| Mini (2 yard) | £75–£150 | £135–£175 |
| Midi (4 yard) | £100–£220 | £145–£235 |
| Builders (6–8 yard) | £220–£420 | £250–£480 |
Swansea prices sit noticeably below London across every size, though the gap narrows on larger builders skips. If a job generates a skip's worth of waste and it isn't priced into the quote, that's a real £100–£400+ coming straight out of profit — wherever you're based.
2. Skip permits
If the skip has to go on a public road rather than a driveway, Swansea Council typically charges around £40–£70 for a permit, and it can take 2–3 days to arrange. London councils charge more — typically £30–£120, sometimes with an extra bay suspension fee of £16–£130 in controlled parking zones. Either way, it's easy to forget until the skip firm asks for one.
3. Parking permits or charges
Daily parking, resident permits, or city centre charges for the van can add up fast on multi-day jobs, especially in town centres or London.
4. Congestion Charge and ULEZ (London jobs)
If a job takes you into central London, the Congestion Charge is £18 a day as of January 2026 (up from £15), and applies Monday to Friday, 7am–6pm. On top of that, a van that doesn't meet Euro 6 emissions standards also faces the separate ULEZ charge of £12.50 a day — both can apply on the same trip, meaning up to £30.50 a day just to get to and from a London job before you've turned a single screw. Swansea and South Wales have no equivalent charge, so this is purely a London-jobs cost to remember.
5. Fuel
Travel to and from site, plus merchant runs, is a real cost that rarely gets its own line on a quote.
6. Waste disposal (non-skip)
Tip runs, licensed waste carrier fees, or specialist disposal (plasterboard, asbestos-adjacent materials) often cost extra beyond a standard skip.
Materials & Equipment
7. Consumables
Screws, sealant, tape, sandpaper, cleaning products — individually cheap, collectively a real cost that rarely makes it onto a materials list.
8. PPE
Gloves, masks, safety glasses, knee pads — replaced regularly, and easy to treat as a sunk personal cost rather than a job cost.
9. Tool wear and replacement
Blades, drill bits, and general tool wear-and-tear happen on every job. Tools don't last forever, and replacing them is a real, ongoing business cost.
10. Plant hire
Mixers, breakers, wacker plates, generators — day or week rates that are easy to underestimate if you don't hire them often.
11. Scaffolding
A two-week scaffold hire for a standard two-storey job typically runs £600–£1,500, plus a council permit of around £140/month if it's on the public highway. This is one of the most commonly underquoted costs on external work.
Time You Don't Bill For
12. Travel time
Driving between jobs and to merchants is time you're not on the tools — but it still has to be paid for somewhere.
13. Material collection time
Queuing at the merchant, loading the van, driving back — often an hour or more that never appears on an invoice.
14. Admin time
Quoting, invoicing, chasing payment, replying to customer messages — unbillable, but very real hours out of your week.
15. Snagging visits and callbacks
A return visit to fix a small issue right after "completion", or a callback for something that surfaces weeks later — both are time and fuel that's easy to write off as goodwill, but if it's not priced into your contingency, it's a straight loss.
16. Site meetings
Walking the job with the customer, architect, or another trade before or during work is time that rarely gets billed separately.
Insurance & Compliance
17. Public liability insurance
An annual cost that has to be recovered somewhere across your jobs — it doesn't pay for itself.
18. Tools insurance
Given the average tool theft claim runs around £1,200, cover is rarely optional — and it's a cost every job needs to help carry.
19. Certification and compliance costs
Gas Safe renewal, Part P certification, NICEIC membership, CISRS cards — annual or periodic fees that need spreading across your pricing.
20. Van insurance and servicing
Your van is a business asset with running costs, not just a vehicle — insurance, MOT, servicing and tyres all belong in your overhead recovery.
Money & Admin Costs
21. Accountancy and bookkeeping
Typically £300–£800 a year for a sole trader — a real cost that needs to be covered by your pricing, not absorbed as a personal expense.
22. Card and payment processing fees
If you take card payments or use invoicing software with payment links, the small percentage fee adds up across a year of jobs.
23. Late payment costs
Every week spent chasing an unpaid invoice is unpaid admin time — and if it drags on, potential cash flow costs too.
24. Variations done for free
Extra work agreed on-site "as a favour" that never gets invoiced. It's still your time and materials — just given away.
25. Contingency for the unexpected
Every job has some risk of something unforeseen — hidden pipework, rotten timber, an extra coat of paint. A quote with zero contingency is a quote betting everything goes perfectly.
Final Thoughts
Underquoting isn't usually caused by charging too little for labour. It's caused by dozens of hidden costs that quietly eat away at profit.
The more consistently you remember them, the more profitable your business becomes.