An AI agent for accounts receivable: how Reva follows up on overdue invoices

Accounts receivable (AR) runs on follow-through. Each open invoice needs a timely reminder with the right contact, amount and tone, and anything sensitive needs a person's judgment. Reva is the AR agent in AgentNava's finance library. This post shows how to automate invoice reminders and overdue invoice follow-up with Reva: what it does each week and what it will never do.

Meet Reva, an AI agent for accounts receivable

Reva is a starter agent: a ready-made agent whose instructions and workflows you can read before you start and change after. Its instructions open with the job:

“You keep cash flowing by tracking every open invoice, sending courteous and timely payment reminders, and surfacing disputes or at-risk accounts to a human before they become write-offs.”

From the instructions Reva follows

Its four workflows are written procedures that it follows step by step:

• Daily AR scan: find what is overdue and draft the day’s reminders.
• Escalating reminder sequence: raise the tone, one step at a time, when an account stays silent.
• Dispute triage: pause and hand off when a customer questions an invoice.
• Payment confirmation: close the loop when money arrives.

Reva works through three connections. A connection is an account you link to AgentNava so an agent can work in it.

• QuickBooks: open invoices, customer contacts, payment terms and aging reports.
• Stripe: payment status for card-billed customers, and confirmation when a payment clears.
• Gmail: reminders go out from your team’s account, and replies come back to it.

All three are listed as Beta in AgentNava’s connections catalog, which means usable today with documented limitations.

Reva’s week at a glance

With one run each morning, a normal week with Reva looks like this:

Every morning: the AR scan, step by step

The daily scan runs in seven steps:

1. Pull every open invoice from the QuickBooks aging report, with invoice number, customer, amount due, due date and billing contact.
2. Check Stripe for card-billed customers. Paid invoices are marked cleared and skipped. Failed charges are tagged for separate follow-up.
3. Sort the remaining invoices into aging buckets by days past due.
4. Draft each reminder from the template for its tier, with the customer name, invoice number, amount, due date, days overdue and payment link.
5. Build a summary: emails by bucket, total outstanding, accounts on hold (skipped), and first-time Critical accounts.
6. Send you the summary and wait for your confirmation.
7. Send the batch through Gmail and log each send.

The bucket sets the tone of each message:

The workflow’s own example run:

“The morning scan finds 23 open invoices. Two cleared overnight in Stripe (marked done). Of the remaining 21: 8 are Current (no action), 5 are Early, 4 are Mid, 3 are Late, and 1 is Critical. Reva drafts 12 emails and surfaces the Critical account (a design agency, invoice INV-1084, 67 days past due, $4,200) separately with a note: ‘First Critical-tier contact for this account. Draft attached.’”

Example run, from the instructions Reva follows. Names and numbers are illustrative.

Overdue invoice follow-up, one tier at a time

When an account stays silent, Reva’s escalating reminder sequence raises the urgency in measured steps. Before each follow-up, Reva checks the latest invoice and email thread, and confirms there is no reply and no dispute flag.

Reva moves an account to the next tier only after enough contact at the current one: one prior reminder for Early, two for Mid, three for Late. From the instructions Reva follows: “Don’t skip tiers. If an account is 45 days past due but has only received one Early-tier email, work through Mid before jumping to Late.”

The tone rises with the tier, from warm and helpful to professional and direct. Firm language is kept for accounts that are 60 or more days past due and have not responded. Automated messages never threaten collections, legal action or credit reporting. People write that language themselves.

After each send, Reva sets a check-back date: 5 days for Early, 7 for Mid or Late, and 3 for a Critical message a person has reviewed.

A Mid-tier reminder from the workflow’s example reads:

“Hi Sarah, a friendly follow-up on invoice INV-2031 for $1,850.00, which was due on July 20. We want to make sure this did not get lost. You can pay securely here: [payment link]. If you have any questions about this invoice, please reply to this email and our team will be happy to help.”

From the instructions Reva follows. Illustrative.

When customers reply and payments arrive

When a customer answers a reminder, the dispute triage workflow takes over. Reva sorts the reply into one of four kinds: a question, a dispute, a request to pay part or agree a payment plan, or a note that the customer has already paid. It puts a hold on the account at once and writes a one-screen handoff summary, with the customer’s own words, for the owner you name. The subject line reads “AR Dispute, [Customer Name], INV-XXXX, [Amount].”

From the instructions Reva follows: “Don’t reply to the customer directly, even to acknowledge receipt. A human makes that first contact.” Only a person can lift the hold.

Payments have their own workflow. When Stripe reports a cleared charge, Reva matches it to the open invoice and checks the amount. For a full payment, Reva drops the invoice from its pending reminders, sends the billing contact a short thank-you, and lists the payment under “Collected Today” in the day’s summary. When a customer says they paid by check or transfer, Reva looks for the payment in QuickBooks and Stripe first. If it is not there yet, Reva notes the claim, checks again in two business days, and tells you.

What Reva will never do

Reva’s limits, from the instructions Reva follows:

• “Don’t move money. You track and communicate. You never initiate refunds, transfers, or charge captures.”
• “Don’t fabricate payment details. Invoice numbers, amounts, and due dates come directly from QuickBooks and Stripe. You never estimate or guess.”
• “Don’t engage with billing disputes. If a customer questions the amount, the service, or the contract, you hand it off. You do not negotiate, apologize for charges, or offer credits.”
• “Don’t contact a customer if the account is already flagged as disputed or on a hold. Check the status before every send.”
• “Never commit to terms. You do not promise payment plans, write-offs, or adjusted amounts.”
• “Don’t alter invoice amounts or due dates in QuickBooks.”

These limits live in Reva’s written instructions, which Reva works from on every run. Treat them the way you treat a handbook for a new AR hire, and connect the accounts you would trust that person with.

How often Reva runs, and what a run costs

Reva is designed to run once each morning. The simplest routine is one message: ask Reva to “Run the daily AR scan.” Reva works through the scan in your conversation, posts the summary there. Keep the routine in that one conversation, so Reva’s log and follow-up dates carry from one morning to the next.

AgentNava can also start an agent on a schedule, a set time when it runs by itself, such as daily at 9:00 in your time zone. A scheduled run works in a conversation of its own, separate from yours. Reva keeps its log in your conversation, so start each daily scan with your morning message.

AgentNava bills by the turn, from prepaid credit. “One turn is one message you send and everything the agent does to answer it.” The price of a turn depends on the agent’s grade, the quality of model it runs on, and ranges from $0.01 to $0.20. A new agent runs at Standard, $0.02 per turn. Your morning message is one turn, and one reply is a second, so a day’s scan with one reply costs $0.04 at Standard. Premium costs $0.05 per turn.

Credit is prepaid and does not expire, and your first $5 is on us. An idle agent costs nothing.

Start with Reva

1. Open Reva’s accounts receivable page, read its instructions and workflows, and choose Start with Reva. AgentNava adds a copy of Reva, with all four workflows, to your agents.
2. Connect QuickBooks, Stripe and Gmail.
3. Add your billing policies to Reva’s instructions: payment terms, grace periods, escalation thresholds, preferred tone, and the person who owns disputes. Add a reminder template for each tier, then publish the draft so Reva works from it.
4. Start a conversation with Reva and ask it to run the daily AR scan. Read the summary it posts.
5. Repeat each morning in the same conversation.

Then read the first week of summaries, and adjust the instructions until they match how your team already works.

Frequently asked questions

How do I set up an AI agent that chases unpaid invoices automatically?

Connect the agent to your accounting system, your payment processor and your email, write your payment terms and reminder tone into its instructions, and have it run each morning. Each run it finds what is overdue, drafts the right reminder for how late each invoice is. On AgentNava you can start from Reva, a ready-made accounts receivable agent: start with it, connect QuickBooks, Stripe and Gmail, add your policies, and ask it to run the daily AR scan. The five steps are in the section above.

What does it cost to run an invoice reminder agent?

A morning scan and one reply are two turns, $0.04 on the Standard grade, so about $1.20 a month if it runs every day. Your first $5 of credit is free. For more worked examples, see how much it costs to run an AI agent for a small business.

Can the agent take payments or issue refunds?

No. Reva tracks invoices and writes to customers. Its instructions say it never moves money: no refunds, transfers or charge captures.