Supplier Invoice & Accounts Payable Software for Construction

The Problem

Supplier invoices arrive by email and post, get keyed into spreadsheets, and are paid without anyone checking them against what was ordered or delivered. Duplicate payments, price creep and over-billing slip straight through.

What Changes

Capture every supplier invoice in one place, match it to the purchase order and goods received note, and only pay what was actually ordered and delivered.

Three-way match: invoice to PO to GRNCatch duplicate, over-billed and no-PO invoicesApproval workflow before any paymentXero and Sage sync with supplier deduplication

How It Works

From the invoice landing in your inbox to a clean payment run, keep accounts payable controlled and auditable.

1
Capture the invoice
Record supplier invoices against the supplier and project with line detail, VAT treatment and due dates — no re-keying into spreadsheets.
The supplier-invoice pipeline — columns for Pending, Awaiting GRN, Ready for Approval, Ready to Pay and Disputed with running totals, plus overdue and ageing flags, and sample invoices from A-Plant (Sunbelt Rentals), Hanson UK and Tarmac Trading Ltd.
2
Match to PO and GRN
Three-way match each invoice to its purchase order and goods received note. Quantity, price and value variances are flagged before approval.
A purchase order with its invoice ledger — line items, the value ordered, the amount billed to date and the outstanding balance — so an incoming supplier invoice can be matched against what was actually ordered and received.
3
Flag variances and duplicates
No-PO, over-billed and duplicate invoices are surfaced automatically so they are queried, not paid.
4
Route for approval
Send matched invoices through a two-stage approval workflow, so the right people authorise spend before any payment.
5
Pay and sync to accounting
Mark invoices ready to pay and push them to Xero or Sage with automatic supplier deduplication, so your ledger stays clean.

Features That Move The Needle

Built for high-stakes construction workflows: deadlines, compliance, and audit trails.

Central invoice capture

Every supplier invoice in one place instead of email folders and spreadsheets.

Three-way matching (invoice, PO, GRN)

Only pay for what was ordered and actually delivered.

Duplicate and over-billing detection

Stop paying the same invoice twice or above the agreed rate.

No-PO invoice flagging

Catch maverick spend that never went through an order.

Two-stage approval workflow

The right people authorise before money leaves the business.

Reverse charge and CIS handling

Handle domestic reverse charge VAT and CIS deductions without workarounds.

Ageing and overdue visibility

See what is due and what is overdue so supplier relationships stay healthy.

Xero and Sage sync

Approved invoices flow to your accounts with suppliers automatically deduplicated.

Seen enough?

Start a 14-day free trial with no card required, or book 15 minutes with Rich (the founder) to walk through your exact workflow.

Why It Works

Three-way matching compares every supplier invoice to its purchase order and goods received note, flagging quantity, price and value variances — and duplicate or no-PO invoices — before payment is authorised. Approved invoices sync to Xero or Sage with supplier deduplication, with a full audit trail from invoice to payment.

Site Samurai — Accounts payable and invoice control

Stop paying invoices twice

Unlimited

Users on every plan

14-day

Free trial, no card required

Xero + Sage

Accounting sync built in

Who It’s For

Accounts / Finance teams
Quantity Surveyors (QS)
Commercial Managers
Directors / Owners
Procurement teams

Already using Site Samurai? Jump to the module features and workflows your team needs.

FAQ

Frequently Asked Questions

Common questions teams ask before they book a demo.

Supplier invoice (accounts payable) software captures the invoices your suppliers send, codes them to projects and cost categories, and checks them against your purchase orders and deliveries before you pay — so you only pay for what was ordered and received.

The platform matches each supplier invoice to its purchase order and its goods received note (GRN). Any variance in quantity, price or value is flagged for review, so over-billing and short deliveries are caught before payment.

Yes. Duplicate, over-billed and no-PO invoices are surfaced automatically so they are queried rather than paid — one of the most common sources of leaked cash in construction.

Yes. Site Samurai supports standard, zero-rated and domestic reverse charge VAT, and applies CIS deductions on labour where relevant, so subcontractor and supplier invoices are treated correctly.

Yes. Approved invoices push to Xero or Sage and suppliers are automatically deduplicated, so your purchase ledger stays clean and reconciliation is straightforward.

No — you can record invoices with or without a PO. Invoices without a matching order are clearly flagged so you can decide whether to raise a retrospective PO or query the spend.