The paperwork that is quiet until it is expensive
CDM applies to every construction project in Great Britain — not just big ones, not just notifiable ones, not just commercial ones. A loft conversion for a homeowner is in scope on day one. Most of what follows is not complicated. It is just unforgiving.
On a domestic job, you are the client too
Regulation 7. A homeowner having work done on their own home does have client duties under CDM — and those duties pass automatically to the contractor. There is no form to sign and no choice in the matter.
Builders who have read that “the client is responsible for X” and assumed that means the homeowner have read it correctly and drawn the wrong conclusion. On a typical extension, X is yours.
The construction phase plan
Nine sections with a prompt on each, written for a real job rather than a template. Issue it and the wording freezes with a server timestamp — because a plan you could date yourself is evidence of nothing.
RAMS, talks and signatures
Hazards scored before and after your controls, so a control that changes nothing is visible. Then the page that usually does not exist: who read what, which version, and when.
Safety is on every plan, free included. A builder on the free tier has exactly the same CDM duties as one on Bespoke. Charging for the means to meet them would be indefensible. The only gated part is a reusable library of risk assessments, which is a convenience rather than a duty.
The deduction comes off the labour, not the invoice
A £6,000 invoice that is £2,000 labour and £4,000 materials carries a £400 deduction at 20% — not £1,200. Taking it off the whole invoice is £800 of somebody else’s money, and an argument on site the same week.
The opposite error is worse and quieter. If a deduction should have been made and was not, HMRC comes to you for the shortfall — not to the subcontractor, who has already spent it. So BuildFlow computes the deduction from a labour figure and a rate, and will not let you pay somebody you have not verified: until HMRC has been asked there is no right answer, and guessing leaves you carrying a liability you do not know about.
Tax months, not calendar months
6th to 5th. A payment on 3 April is a different return from one on 6 April, and getting it wrong is a correction. BuildFlow works the month out from the date the money moved.
Every statement, one PDF
A page each, with the gross, the materials and the deduction HMRC specifies. A builder who has to make fourteen separate documents makes none of them.
The dates, and what missing them costs
BuildFlow counts the days and puts the number on your dashboard. It is late for the most ordinary reason there is — nobody was counting.
| What | When | Late |
|---|---|---|
| CIS monthly return | By the 19th | £100 the day after. £200 at two months. £300 or 5% at six, and again at twelve. |
| Pay HMRC the deductions | By the 22nd, electronically | Interest, and it counts against you. |
| Subcontractor's payment and deduction statement | Within 14 days of the tax month ending | They cannot prove the tax you took off them. |
| RIDDOR: over-seven-day injury | Within 15 days of the accident | An offence, and an HSE conversation you start on the back foot. |
| Construction phase plan | Before anybody sets foot on site | The document an inspector asks for first, and the one you cannot write afterwards. |
A defects period is not a limitation period
Six or twelve months is a contractual arrangement about who comes back and fixes things for free. It says nothing about how long a homeowner can bring a claim.
Under the Consumer Rights Act 2015 a service must be carried out with reasonable care and skill, and a homeowner generally has six years to bring a claim in England and Wales — five in Scotland. A builder who believes their exposure ends at month twelve is wrong.
So BuildFlow does not close the defects register when the period ends. A defect reported afterwards is recorded like any other and marked as outside the period. What changes is who pays, not whether it exists — and the record is what answers a claim three years later.
What BuildFlow deliberately does not decide
Every one of these is a judgement with a bill attached, and a confident wrong answer is worse than no answer because somebody acts on it.
Whether your job is notifiable
It applies the 30-day and 20-worker test and flags when the person-day bound clears 500. The judgement stays yours, because the second limb depends on numbers the app cannot see.
Whether an incident is RIDDOR reportable
It puts the five tests in front of you and records your answer. A confident wrong "not reportable" is worse than no answer, because somebody acts on it.
Which VAT rate applies
It states the test for 20%, 5% and zero rated. Getting it wrong is an assessment plus interest years later, and the test turns on how long a property was empty or whether a conversion changed the number of dwellings.
Whether a control measure is adequate
It scores what you tell it and shows you the residual risk. It cannot see your site.
Filing anything with HMRC
It works out the figures and counts the days. You submit on HMRC's own service, and marking a month filed is a note to yourself that you have.
Where the answer matters and you are not sure, the guidance is free and written for small builders: HSE’s CDM 2015 pages and its RIDDOR pages on hse.gov.uk, HMRC’s CIS340, and VAT Notice 708.