PO-Flip Supplier Invoice Portal

The problem this kills

Suppliers invoice you however they like. A free-form PDF lands in the AP inbox with a price that drifted from the PO, a quantity higher than what you ordered, a line item nobody recognizes, or a different unit of measure. Now someone in accounts payable has to play detective: pull the PO, pull the goods receipt, eyeball three documents side by side, and email the vendor to fix it. Multiply that by hundreds of invoices a month and you have a queue that never empties, late-payment penalties, and duplicate payments that slip through.

The root cause is simple: you let the supplier decide what the invoice says. This tool flips that. Instead of the supplier typing an invoice from scratch, they open your purchase order and turn it into an invoice - and the only thing they can do is confirm a line or bill less than what was ordered and received. Prices are locked to the PO. Quantities are capped at what you actually received. The "mismatched invoice" mostly stops existing, because there is nothing left to mismatch.

What you'll build

A secure web portal with two sides:

• The supplier side: a vendor clicks a link, sees the open lines on their PO (already filled in with item, ordered quantity, received quantity, and locked unit price), confirms or reduces each line, adds their own invoice number plus tax and freight, and submits. They physically cannot bill more than ordered, cannot change the price, and cannot invent line items.
• Your side: the buyer or AP reviewer gets notified, opens the flipped invoice, sees any place where the submitted quantity differs from the receipt highlighted, and either accepts it into your match queue or sends it back. Nothing reaches your AP system until a human accepts it.

The result is a matchable invoice record - PO-aligned, receipt-capped, deduplicated - that you can hand straight to 3-way match, or export as a clean CSV in exactly the columns your ERP or accounting system expects.

What's inside the Implementation Plan

The plan is a single file you paste into an AI coding agent (Claude Code). It builds the whole thing with you, step by step, in plain language - no prior coding needed.

It opens by interviewing you about your business so the tool fits how you actually buy. It is not a generic template: the agent asks about your PO numbering, your item and SKU conventions, whether you cap billing at ordered or received quantity, how you handle tax and freight, your tolerance rules, and your messiest exceptions - then it shapes the data model, the validations, and every later step around your answers and reads a short spec back to you for a thumbs-up before it builds anything.

From there it walks through standing up the database, the supplier flip screen, the validation rules that lock prices and cap quantities, the AP review-and-accept gate, the email notifications, and the CSV export - each step ending in a ready-to-paste prompt.

The governance it includes (this is the point)

This is not a toy form. The plan bakes in the controls AP and audit actually require:

• Login so only your team can reach the review side; suppliers reach only their own PO via a signed, expiring link.
• Row-level security so a supplier sees only their PO and your team sees only your organization's data - never another tenant's.
• A complete audit trail - who opened the PO, what they submitted, who accepted or rejected it, and exactly when.
• A hard human-in-the-loop approval gate - the supplier submits, your reviewer accepts. Nothing enters the match/AP queue until a person signs off, especially when quantities or amounts differ from receipts.
• Duplicate guards - one flip-invoice per PO + supplier-invoice-number, and fully-billed lines are blocked from being re-flipped, so the same charge can't sneak through twice.

Who it's for

AP and procurement teams who are tired of reconciling free-form supplier invoices by hand and want to constrain what suppliers can bill in the first place. If you issue purchase orders and receive goods against them - and you'd rather suppliers confirm your numbers than invent their own - this is for you. You don't need to be a developer; you need to know how your business buys, and the plan handles the rest.

You've got this - paste the first prompt and let the agent interview you.