How to build an accounts payable and invoice approval workflow

Vendor invoices arrive by email, by mail, through vendor portals and sometimes handed over by a field manager. Someone in accounting prints or forwards them, chases a manager for approval, waits, chases again, and keys the approved ones into the accounting system. Meanwhile a vendor calls about a past-due bill nobody knew existed, and the controller wonders whether last month's duplicate payment was the only one.

An accounts payable approval workflow brings order to everything between "invoice received" and "invoice paid." This guide covers what the current way costs, exactly what the app should contain, an example request you could hand to FORGE, a rollout plan, mistakes to avoid and how to measure results.

What the current way costs you

• Invoices get lost in inboxes. A forwarded email sits unread with a manager on vacation. Nobody else can see it.
• Late fees and lost discounts. When approvals take weeks, early payment discounts expire and late fees appear.
• No audit trail. "Who approved this?" means searching emails. An auditor asking the same question costs hours.
• Duplicate payments. The same invoice arrives by email and by mail, or gets resent as a reminder, and both copies get paid.
• Unclear coding. Managers approve the amount without checking the account or department. Month-end reports suffer.
• Fraud risk. Fake invoices and requests to change a vendor's bank details are a well known scheme. Informal processes make them easier to slip through.
• Rigid AP software. Some dedicated AP products are priced for larger finance teams, charge per approver, or force an approval structure that does not match yours.

What the app should contain

Intake

Every invoice should enter the same way. Set up a dedicated AP email address that feeds the app, plus an upload button for paper invoices scanned at the office and a phone camera option for field managers. The app reads the key details from the invoice: vendor, invoice number, invoice date, due date, amount, tax and line items. The AP clerk reviews and corrects them. The original file is always attached.

Vendors

Each vendor record holds the legal name, contacts, payment terms, default account and department, whether a purchase order is required, any tax forms on file, and the remittance details. Changes to remittance details should require a second approver and be logged, with a note that the change was verified by phone using a number from your own records.

Coding

Each invoice, or each line, is coded to an account, a department or location, and a project or job if you track them. Defaults come from the vendor and the purchase order. The approver sees the coding and can question it.

Matching

When there is a purchase order, the app shows the PO and any receipt or delivery confirmation next to the invoice and flags differences in quantity or price above a tolerance you set. When there is no PO and the vendor requires one, the invoice is held for the AP clerk.

Approval routing

This is where most of the value lives. Rules decide who approves, for example:

• Up to a first limit: the department manager
• Up to a second limit: the department director as well
• Above that: the CFO or owner as well
• New vendors, or first invoice from a vendor: AP lead review first
• Specific categories, such as capital purchases or legal fees: a named approver

Approvers get a notification with the invoice, the PO, the coding and an approve or reject button, on their phone or computer. A rejection needs a reason. A delegate can be set while someone is out, so invoices do not stall.

Statuses

1. Received: captured, details read
2. Needs review: AP clerk is checking details, coding, PO and duplicates
3. On hold: missing PO, possible duplicate, or a question to the vendor, with a reason
4. Pending approval: with the named approver
5. Approved: all approvals complete
6. Rejected: returned with a reason
7. Sent to accounting: passed to your accounting system
8. Paid: payment date and method recorded

Controls

• Duplicate check on vendor plus invoice number, and on vendor plus amount plus date
• Nobody approves an invoice they submitted
• Nobody approves above their limit
• Vendor bank detail changes need a second person
• A complete record of who did what, when

Payment handoff

Approved invoices go to your accounting system, by a scheduled export or a direct connection. Your accounting system remains the books of record and usually runs the actual payment. When payment is made, the paid status and date come back so anyone can answer a vendor's "when will I be paid" question.

Roles

Notifications

• Approver: when an invoice needs them, and a daily reminder for anything waiting more than a set number of days
• AP clerk: when an invoice is rejected or a hold is resolved
• Controller: weekly list of invoices due in the next 10 days that are not yet approved

Reports

• Invoices by status and age
• Approval time by approver and department
• Invoices due soon and not approved
• Discounts captured and missed
• Spend by vendor, account and department
• Holds by reason

Example request

Here is an example request a controller could hand to FORGE in plain words. Change the limits, departments and steps to match yours.

"We are a 60-person distribution company with about 300 vendor invoices a month. Build an AP approval app. Invoices come in to ap@ our domain, and the app reads the vendor, invoice number, dates, amount and lines. Our AP clerk reviews each one, codes it to an account and one of our four departments, and checks it against the purchase order if there is one; flag any price or quantity difference over 2 percent. Flag possible duplicates by vendor and invoice number, or same vendor, amount and date. Department managers approve up to $5,000, the operations director up to $25,000, and our owner above that. Any new vendor goes to the controller first. Rejections need a reason. Nobody can approve an invoice they entered. Managers approve from their phones. Approved invoices export each afternoon in a format our accounting system imports, and we mark them paid when the payment runs. Only the controller can change a vendor's bank details, and that change needs the owner to approve it too. I want reports on approval time by manager, invoices due in the next 10 days not yet approved, and spend by vendor and department."

Rolling it out

1. Write down your approval rules. Limits, departments, special categories and who covers whom. If the rules exist only in people's heads, this step pays for itself.
2. Clean the vendor list. Merge duplicates, confirm terms, and verify remittance details for your top vendors.
3. Set up the AP inbox. Tell vendors, starting with the largest, to send invoices there.
4. Pilot with one department. Run every invoice for that department through the app for a month, side by side with your accounting close.
5. Check the handoff. Make sure approved invoices land in your accounting system exactly as expected, with the right coding.
6. Bring on the remaining approvers. A short walk-through on a phone is usually all managers need.
7. Turn off the old path. Stop accepting approvals by email reply. If someone forwards an invoice, the AP clerk adds it to the app.
8. Review rules after one quarter. Adjust limits that send too much to senior people, or too little.

Mistakes to avoid

• Rebuilding the books. The app handles approval. Your accounting system keeps the ledger and usually pays. Keep that line clear.
• Rules nobody agreed to. Build the rules your finance lead and owner have signed off on, not a guess.
• No delegate. Invoices stall the moment an approver goes on vacation. Make delegation a two-tap action.
• Approving without seeing the invoice. Approvers should see the actual document, the PO and the coding on one screen.
• Trusting emailed bank changes. Always verify by phone using a number you already have.
• Ignoring the long tail. Small invoices pile up. Consider a low-amount rule that routes them faster rather than skipping review entirely.

Tax, retention and payment rules vary by country and state. Confirm what records you must keep, and for how long, with your accountant or tax advisor.

How to measure that it works

Launch checklist

1. Approval limits and special rules written and signed off
2. Vendor list cleaned and remittance details verified
3. AP inbox created and vendors told
4. Coding defaults set by vendor
5. Duplicate checks tested with real past invoices
6. Separation of duties rules in place
7. Delegation tested
8. Accounting handoff tested end to end
9. Pilot department run for one month
10. All approvers invited and shown the phone view
11. Email approvals retired
12. Quarterly rules review on the calendar

How FORGE handles it

FORGE lets your controller describe the invoice workflow in plain words and get a working approval app back, and most teams have their first real tool the same day. A panel of top AI models plans it around your vendors, limits and accounting handoff, a dedicated AI crew builds it, and every piece is checked for quality and security before it is saved. The AP team works on the web and managers approve on their phones.

The app lives inside your company, people join only by invite, each role sees only what it should, and there is a complete record of who did what, which is exactly what an auditor asks for. Managers who only approve are free, so every approver can be in the app. When your limits change, you describe the change and the workflow follows; changes cost a small fraction of a build and only count when something changes. Nothing bills by itself, and there are caps and alerts at 80 and 100 percent. Our team starts every company with a workflow workshop, and AP is a common first tool. Talk to us or see pricing.

Questions people ask