Construction Purchase Order & Approval Software

The Problem

When purchase orders live in spreadsheets and email chains, spend gets committed without proper approval and invoices arrive with no audit trail.

What Changes

Create, approve, send and track purchase orders from one place with built-in budget control, GRN matching, and accounting sync.

Multi-level PO approval with spend limitsThree-way matching: PO to GRN to invoiceReverse charge VAT and CIS handlingXero and Sage sync with supplier deduplication

How It Works

From requisition to invoice match, keep procurement controlled, visible, and auditable.

1
Create the purchase order
Add line items, categories, cost codes and VAT treatment. Assign to a project or mark as overhead.
The Purchase Orders list — 32 active POs with a total committed value of £1,710,109, including a Labour order for a Traffic Management Crew from Hanson UK on Harrogate Station Gateway at £20,250, a Plant order for a 6T Mini Excavator Hire from GAP Group Ltd at £19,150, and a Materials order for Type 1 Sub-base MOT from Breedon Group at £34,985, all searchable by PO reference, supplier or item.
2
Route for approval
Configurable 1-3 level approval workflow with per-user spend limits and threshold rules.
A single purchase order — PO-2023-019-006 for Hanson UK on the Harrogate Station Gateway project, with line items (a Traffic Management Crew, 21 days at £650 for £13,650; a Kerbing Gang of 3, 6 days at £1,100 for £6,600) totalling £20,250, an invoice ledger showing £0 billed and £20,250 outstanding, and a created, approved and sent timeline.
3
Send to supplier
Generate a professional PDF and email directly to the supplier from the platform.
4
Track delivery (GRN)
Record goods received notes against the PO, flag discrepancies, and run quality checks.
5
Match supplier invoice
Three-way match: PO to GRN to supplier invoice. Flag variances before payment.
The supplier-invoice three-way-match pipeline (PO to GRN to invoice) — columns for Pending, Awaiting GRN, Ready for Approval, Ready to Pay and Disputed, with overdue totals and real invoices from A-Plant (Sunbelt Rentals), Hanson UK and Tarmac Trading Ltd.
6
Sync to accounting
Push approved invoices to Xero or Sage with automatic supplier deduplication.

Features That Move The Needle

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

PO creation with line items and cost codes

Consistent, detailed orders that map directly to your project budgets.

Multi-level approval workflow

Ensure the right people sign off before money is committed.

Per-user approval limits

Control who can approve what value — no more rogue spending.

PDF generation and supplier email

Professional documents sent directly — no manual exports or attachments.

Multiple VAT modes

Handle standard, zero-rated, and reverse charge VAT without workarounds.

Project vs overhead PO distinction

Separate project procurement from overheads for cleaner cost reporting.

GRN and delivery tracking

Know what arrived, what is outstanding, and flag discrepancies early.

Three-way invoice matching

Catch variances between order, delivery, and invoice before you pay.

Seen enough?

Start a 14-day free trial — you won’t be charged until it ends, or book 15 minutes with Rich (the founder) to walk through your exact workflow.

Why It Works

Three-way matching compares every purchase order to goods received notes and supplier invoices, flagging variances before payment is authorised. Configurable multi-level approvals with per-user spend limits ensure the right people sign off at every stage, with a full audit trail from requisition to invoice.

Site Samurai — Purchase order and procurement control

Catch variances before you pay

Unlimited

Users on every plan

14-day

Free trial — cancel anytime

Xero + Sage

Accounting sync built in

Who It’s For

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

Purchase order software lets you create, approve and track orders to suppliers digitally. In construction, it ties POs to projects, cost codes and budgets so you know exactly what has been committed and what has been delivered.

You configure 1 to 3 approval levels with per-user spend limits. When a PO is raised, it routes to the right approvers based on value and project. Approvers can approve, reject, or query from web or mobile.

Yes. Goods Received Notes (GRNs) are raised against POs so you can see what has arrived, flag short deliveries or quality issues, and maintain a full delivery audit trail.

Yes. Site Samurai syncs with Xero and Sage, pushing approved invoices and automatically deduplicating suppliers so your accounts stay clean.

The platform matches the purchase order to the goods received note to the supplier invoice. Any variance in quantity, price or value is flagged before payment is authorised.

Yes. Site Samurai supports standard VAT, no VAT, and reverse charge VAT — configurable per PO line item.

Yes — use the interactive demo to explore the full PO workflow, then book a guided walkthrough for your specific procurement setup.