How to build AP invoice processing

What matters here

• Take invoices from where they already arrive. Mandating a portal means half of them still come by email and nobody watches that inbox.
• Score the extraction and check the uncertain ones. A confident wrong number posted to the ledger is worse than a slow one.
• Detect duplicates before posting, on supplier plus invoice number plus amount. The same invoice arrives twice more often than anybody expects.
• Never post an unmatched invoice to clear payment. Hold it, name an owner and show the discrepancy.
• Track early payment discounts by deadline. They are free money and they expire in a queue.

Who this is for

You run accounts payable or finance systems. Invoices arrive by email, portal and post, somebody keys them in, and the month end backlog is a known quantity everybody plans around.

How it works in practice

What has to happen between an invoice arriving and a supplier being paid.

1. 1

   Invoices are taken from every channel they arrive on

   A shared mailbox, a supplier portal, and a folder somebody drops scans into. Not one mandated route.

2. 2

   Extraction produces values with confidence scores

   Supplier, invoice number, date, line items, tax and total, each scored instead of asserted.

3. 3

   Anything uncertain goes to a person before posting

   High confidence posts, the middle band is checked, and low confidence is keyed by hand with the image alongside.

4. 4

   Duplicates are caught before anything reaches the ledger

   Supplier plus invoice number, then a fuzzy pass on amount and date for the ones that were re-sent slightly differently.

5. 5

   The invoice is matched against its purchase order

   Within tolerance clears, outside it stops with the discrepancy shown.

6. 6

   Payment is scheduled against terms and discounts

   Early payment discounts surfaced before the deadline, not reported after it.

Paste these into Claude Code or Codex with the Tray Headless plugin installed. Each stage runs on its own. The systems named in them are the worked example rather than a requirement, and every prompt says so.

Once per project, run /tray-workflows:set-workspace to pick the workspace these build in. Point it at a sandbox first.

1. 1

   Start here: take invoices from every channel

   Because a mandated portal captures the compliant suppliers only.

   Headless skills build-workflow

   Copy

   Use build-workflow. The systems in play are Gmail, NetSuite, Coupa,
   Google Drive, Slack and Snowflake, or whatever we run in those seats.
   Before you plan anything, tell me which of them are already
   authenticated in the workspace, because I do not want a connector
   stubbed that I have not authenticated.
   
   Build intake from all of these into one queue, landing each as a
   NetSuite VendorBill draft matched against its PurchaseOrder and
   ItemReceipt:
   
     The shared AP mailbox, attachments only, ignoring the reply chains
     The supplier portal, where suppliers who use it upload
     A watched folder for scans and anything forwarded on
   
   Normalise them into one record with the source, the original file, and
   the arrival timestamp. Keep the original file forever. It is the evidence
   and it will be asked for.

2. 2

   Extract with confidence, and check the uncertain ones

   The step where trusting a model too far becomes an overpayment.

   Headless skills build-workflow

   Copy

   Use build-workflow. Extract supplier, invoice number, invoice date, due
   date, currency, line items, tax and total, and give each field a
   confidence.
   
   Then band the result:
   
     every field above the high threshold   post straight through
     anything in the middle band            queue for a quick human check
     anything low, or a total that does not equal the sum of lines plus tax
                                            key it by hand
   
   Always show the original image beside the extracted values in the review
   screen. A reviewer checking numbers against a form they cannot see is not
   checking anything.
   
   Never post a field the model was unsure about. A confident wrong total
   becomes a payment.

   The arithmetic check is the cheapest control here. If lines plus tax does not equal the total, extraction has misread something regardless of how confident it was.

3. 3

   Catch duplicates before anything posts

   The same invoice arrives twice more often than anybody expects.

   Copy

   Before posting, check for duplicates in this order:
   
     Exact: same supplier and same invoice number, ever
     Near: same supplier, same amount, within a few days, different number
     Fuzzy: same amount and date across two supplier records that may
     themselves be duplicates in the vendor master
   
   Block the exact ones outright. Flag the near ones for review with both
   invoices shown side by side.
   
   Suppliers re-send. A chased invoice arrives again with a new reference,
   and a statement re-sends everything outstanding. Both of those look like
   new invoices to anything checking only the number.

4. 4

   Match, and route what does not

   So the only invoices anybody touches are the ones that need touching.

   Headless skills tray-gotchas

   Copy

   Use tray-gotchas, then match against the purchase order and receipt with
   tolerances I can set.
   
   Within tolerance clears for payment. Outside it stops and routes to a
   named person with the order, the receipt and the invoice side by side and
   the difference highlighted.
   
   Handle these:
   
     No purchase order at all. Route to the cost centre owner to confirm and
     attach one, do not reject and do not pay.
     Partial delivery. Pay for what arrived, keep the balance open.
     Credit note. Match it to the original invoice rather than treating it
     as a negative invoice floating on its own.
     Supplier not in the vendor master. Stop. A new supplier is an onboarding
     process, not an invoice field.

5. 5

   Schedule payment against terms, and chase the discounts

   Early payment discounts are free money that expires in a queue.

   Copy

   Schedule payment from the supplier terms rather than the invoice date,
   and surface early payment discounts before their deadline, not after.
   
   Report weekly: invoices processed by channel, straight-through rate,
   average days to process, exceptions by reason, duplicates caught, and
   discounts available against discounts taken.
   
   That last pair is the number that pays for this. A discount missed
   because an invoice sat in a queue is a cost with nobody attached to it.

6. 6

   Validate, then hand the thresholds to AP

   Because tolerances and confidence bands are finance judgement.

   Copy

   Run the per-step schema checks and the whole-workflow audit before this
   touches production. Run in review-everything mode for a fortnight first,
   so the confidence thresholds are set from real invoices, not 
   guessed.
   
   Then open the same workflow in Tray Build so accounts payable can move
   the confidence bands and the matching tolerances in the visual canvas.

What it connects to

Invoices arrive in several places and end up in one ledger.

Named systems are the ones most teams run, not the only ones that work. Each is an authentication in your Tray workspace, referenced by name, so the workflow never holds a credential. Where we have a connector page, the name links to it.

Questions people ask

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