Invoices and billing

Flow Payroll’s billing module lets you raise invoices for the businesses you run payroll for — for example as a staffing agency or bureau — issue and apply credit notes, and send everything to a connected accounting system such as Xero. Invoices are created per client and can be generated automatically when payroll syncs to billing, or built manually.

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Invoices

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Invoice lifecycle

An invoice moves through the following statuses:

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Viewing invoices

Navigate to Invoices in the main menu to see all invoices across all clients in a single table. You can also view invoices scoped to one client from the client detail page. Filter invoices by status, invoice type (Sales or Purchase), client, amount range, date range, attachments, or line-item warnings (missing attachments, missing PO number).

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Invoice detail

Select any invoice row to open the detail view. It shows:

• Invoice details — client, organisation, amount, balance due, status, type, format, dates, invoice number, reference, currency, and line amount type
• Line items — a table of every line, with amount, tax, account code, and any warnings
• Summary — subtotal, VAT / total tax, total, credits applied, and total balance due
• Credit applied — credit notes allocated against this invoice
• Attachments — documents uploaded at the invoice or line-item level

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Editing a draft invoice

On a Draft invoice, you can change:

• Invoice type — Sales or Purchase
• Due date
• Invoice number
• Reference — e.g. a PO number or internal reference
• Currency — GBP, USD, or EUR
• Line amount type — Exclusive (amounts exclude tax) or Inclusive (amounts include tax)

Select Save details to apply changes. Once an invoice moves to Issued or beyond, these fields are locked.

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Voiding an invoice

On the invoice detail view, select Void invoice to cancel an invoice. Voiding is permanent and cannot be undone.

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Invoice attachments

You can upload supporting documents (PDF, Word, image files) to a draft invoice directly from the invoice detail view. Uploaded files appear in the Invoice attachments section and can be downloaded or deleted while the invoice remains a draft. Line-item level attachments are uploaded and managed per line in the line items table. The invoice header shows a count of line-item attachments separately.

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Sending to your accounting system

If you have connected an accounting system, select Send on the invoice detail view. Nothing goes across on its own — closing an invoice does not send it — so an invoice reaches the customer’s ledger only when somebody decides it should. Once it has landed, a Download PDF button appears to retrieve the rendered document. Attachments on the invoice and its line items follow the invoice once the accounting system has it.

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Credit notes

A credit note reduces an amount owed by a client. You can create a credit note standalone (leaving credit on the client’s account) or allocate it directly against a specific invoice.

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Credit note lifecycle

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Creating a credit note

You can create a credit note from two places:

• The Credits tab on a client detail page
• The Credit applied section on an invoice detail view (when the invoice is in Draft or Issued status)

There are two creation modes:

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Authorising and allocating credit

A credit note must be Authorised before it can be applied to an invoice. To apply credit to an invoice:

1. Open the invoice detail view.
2. In the Credit applied section, select Apply credit.
3. Choose the authorised credit note and enter the amount to allocate.
4. Confirm.

The invoice’s balance due updates immediately. You can remove an allocation from the same section while the invoice is still in Draft. To apply a full credit — creating a credit note for the full invoice amount and allocating it in one step — use Credit entire invoice on the invoice detail view.

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Credit notes on the client page

The Credits tab on a client detail page lists all credit notes for that client with their original amount, available balance, status, and any allocations. Expand a row to see usage (which invoices the credit has been applied to and for how much).

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Finance settings

Finance settings control how invoices and credit notes are created for a client. Configure them in the Finance settings section on the client detail page, or set organisation-wide defaults in Settings → Billing. Key settings: For full details on client-level finance configuration, see managing clients.

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Sending to your accounting system

Flow Payroll can send invoices and credit notes to a connected accounting system. Each one is sent when you press send; none of it happens on its own.

• Clients are sent as contacts, either on their own or carried along with the first document that names them.
• Invoices are sent individually or in bulk.
• Credit notes are sent with their allocations, so the customer’s balance is right in one step.
• Status is visible on each invoice, credit note and client row, and reflects what the accounting system last told us.

Connect the account under Settings → Integrations, then choose it for billing under Settings → Billing → Accounting system. See connecting your accounting system. You can also import existing contacts as clients: see managing clients.

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Where to go next