Invoicing and VAT
Raising a numbered VAT invoice from what the job already says is owed, the two dates that matter, credit notes, and the export your accountant wants.
Updated 16 September 2026
An invoice is not a screen. It is a legal document with contents the law specifies, a number that has to be unique and sequential, and a rule that it does not change once it has gone out. BuildFlow is built around those three facts, which is why a few things work differently from how you might expect.
Raising one
Invoices → New invoice, or from a job's Money tab. It opens on everything that job says is owed and not yet billed — payment stages that are due, and approved changes you have not invoiced — all ticked, at the VAT rate the project was agreed at.
Untick what you are not billing yet. That list is most of the reason to invoice here rather than in a spreadsheet: BuildFlow knows what you have already asked for, so you do not have to.
A draft has no number
Numbers are assigned when you press Issue, not when you press New. Open four drafts on a Tuesday and bin three and you have not used up INV-0043 to INV-0045. HMRC accepts gaps you can explain, but "I clicked New a lot" is a conversation nobody wants.
A draft is yours alone — your client sees nothing until you issue it, and they cannot download a PDF of it.
The two dates
Issuing asks for three dates and the middle one is the reason it is a dialog rather than a button.
| Date | What it is | Get it wrong and |
|---|---|---|
| Invoice date | The day you raised it | Nothing much |
| Date of supply | The tax point — when the work was actually done | It lands in the wrong VAT quarter |
| Payment due | When you expect to be paid | Your chasing is out by a fortnight |
Finish in one quarter, invoice in the next
This is the case builders get wrong unaided. Work completed on 29 June and invoiced on 2 July belongs in the quarter that ended in June, not the one that just started — so set the date of supply to when you finished. BuildFlow defaults it to the invoice date, which is right most of the time and wrong exactly when it matters.
VAT
The rate sits on each line, not on the invoice, because one job mixes them: a zero-rated new build with a bit of 20% repair work on the side. The invoice shows the rate against each line and a breakdown at the bottom giving the net and the tax at each rate, which is what regulation 14 requires and what your client's accountant reads first.
- 20% — the standard rate. Most repair, maintenance and improvement work.
- 5% — the reduced rate. Some conversions, some renovations of long-empty homes, certain energy-saving materials.
- 0% — zero-rated. New build, some conversions, some work for disabled people.
BuildFlow will not tell you which rate applies
It records the rate you enter and does the arithmetic correctly. Which rate a piece of work attracts is a question for your accountant and for HMRC's own guidance — the rules on conversions and renovations in particular are narrower than people assume, and getting one wrong is expensive in both directions.
The domestic reverse charge does not apply to homeowners
It catches construction services between VAT-registered businesses inside the CIS chain. A homeowner is an end user, so a builder invoicing them charges VAT the ordinary way. Reverse charge becomes relevant between you and your subcontractors, not on these invoices.
If you are not VAT registered, tick nothing: BuildFlow leaves the VAT number, the tax column and the breakdown off entirely, and the document says "Invoice" rather than "VAT Invoice". Printing "VAT at 0%" on your behalf would invite exactly the wrong question.
Retention
An invoice can hold back a retention, shown as a deduction from the net. VAT is charged on the full value of the work, before the deduction — the invoice says so in a line at the bottom.
There is a concession, and it is worth asking about
HMRC allows the tax point for retained amounts to move to when they are actually paid. Applying it means splitting the document, which BuildFlow does not do — a wrong guess about somebody's VAT period is worse than a conservative one. If you hold retention regularly, ask your accountant whether you should be using it.
Once it has gone out
Nothing on an issued invoice can be changed. Not the lines, not the totals, not your address — because the copy your client has says what it says, and a document that can quietly change under them is not a record of anything.
| Use it when | What happens | |
|---|---|---|
| Void | It should never have gone out — wrong project, wrong client, duplicate | Keeps its number, marked void. Nothing was ever owed. Refused if money has been received against it |
| Credit note | It was right when you sent it and has to be reversed | A new document, numbered CN-, that you can trim to credit only part of the original. Both stay in your VAT return |
Why a credit note is numbered CN and not INV
It takes the next number in the same sequence, so there are no gaps to explain, but it wears a different prefix. A credit note numbered INV-0045 is a page that says "invoice" at the top and credits money, and somebody's bookkeeper will file it wrong.
Getting paid
Your client pays you the way they already do — bank transfer, mostly. Put your account details in the footer under Company → Invoicing and they appear at the bottom of every invoice. An invoice without the account on it gets a phone call instead of a payment.
Record what arrives with Record a payment. Part payments are the norm and BuildFlow expects them: the status follows the arithmetic rather than being something you choose. When an invoice is settled in full, any payment stage it was billing is marked paid too.
BuildFlow does not take the money
There is no card payment and no "pay now" button, deliberately. Handling client payments would make BuildFlow a payments facilitator — ID checks on every builder, liability for chargebacks, payout support — which is a different business, not a missing feature.
Chasing
Two nudges: one a few days before an invoice falls due, one when it has. Then it stops. Chasing an unpaid invoice properly is a phone call with a relationship behind it, and an app that emails your customer every Monday about money is an app you would turn off. Overdue invoices stay red on your dashboard, which is what prompts the call.
Your accountant's copy
Export on the invoices screen gives a CSV for a VAT quarter: one row per invoice line, with the rate and the tax broken out on each. That is the shape a bookkeeper wants — a per-invoice export makes them re-derive the rate split by hand on exactly the jobs where it is mixed.
- Filtered on the date of supply, not the invoice date, so nothing falls between two quarters.
- Credit note lines come out negative, matching their totals.
- Drafts are left out — a row for a document that does not exist yet only causes questions.
- Opens correctly in Excel, Numbers and every accounting package worth the name.
There is no Xero or QuickBooks integration, and that is a choice rather than an omission: builders change accountant more often than they change bank, and every package imports CSV.
Your numbering
Set your prefix and payment terms under Company → Invoicing. The counter itself cannot be changed — a series with a repeat in it is worse than one that started from the wrong place, and uniqueness is the one thing HMRC actually asks about.
Which plans have it
Pro and above. The contract sum, scope, payment schedule, changes and choices are all on Basic; invoicing is the point at which somebody is running a business rather than a job.