Automated overdue invoice reminders from Xero with Gmail and Slack

Build me an overdue-invoice dunning agent that runs on a cron every weekday at 8am in my local time zone.

Each run, use Xero List Invoices to fetch every invoice with status AUTHORISED whose DueDate is in the past. Group the results by contact. For each contact, call Xero Aged Receivables by Contact Report to enrich them with their total outstanding balance and aging buckets (Current, 1-30, 31-60, 61-90, 90+).

For each overdue contact, draft a personalised reminder email whose tone scales with how overdue their oldest invoice is. 1 to 14 days late: a friendly nudge that lists the invoice numbers, amounts, and due dates. 15 to 45 days late: a firmer follow-up that also includes the full statement of outstanding invoices and the total amount due. 46+ days late: an escalation note that signals the account is being flagged for human review and asks the customer to reply with a payment plan. Keep the writing warm and professional, use the contact's first name when available, and reference real invoice numbers and dollar amounts from Xero, never placeholders.

Send each draft as a real email via Gmail Send a Message to the contact's primary email address on file in Xero. Use a clear subject line that includes the customer name and the total amount overdue.

After all emails have been sent, post a single Slack summary via Slack Send a Message to a channel I will configure (default #finance). The summary should list each customer that was emailed, the total dollars chased across the run, and a separate callout for any accounts that hit the 46+ day escalation threshold.

Guardrails. Do not double-send: before emailing a contact, check whether they were already chased in the last N days (default 4) and skip them if so. Track this in agent memory or a small state file so consecutive runs do not repeat. Never email a contact whose overdue invoices are fully offset by a credit note or overpayment in Xero, even if the invoice still shows as AUTHORISED. If Xero returns zero overdue invoices, skip the email step entirely and post a short 'nothing to chase today' note to Slack.

Make the schedule, the Slack channel, the look-back window, and the tone-band cutoffs (14 days, 45 days) easy to change at the top of the instructions.

Additional information

What does this prompt do?

Pulls every overdue invoice from Xero each weekday morning and groups them by customer
Drafts a personalised reminder email whose tone scales with how late the oldest invoice is, from a friendly nudge to a firm follow-up to an escalation note
Sends each reminder from your Gmail to the customer's primary contact and skips anyone with a credit note or overpayment already on file
Posts a single Slack summary listing who was chased, the total dollars chased, and any accounts that have crossed the escalation threshold

What do I need to use this?

A Xero account with permission to read invoices, contacts, and the Aged Receivables report
A Gmail account that the reminders will be sent from
A Slack workspace and a channel where the daily summary should be posted

How can I customize it?

Change the send time, the days it runs, or the time zone the schedule uses
Adjust the tone bands, for example treat anything past 30 days as the firm follow-up instead of 45
Pick a different Slack channel for the summary or route escalations to a separate channel
Tune the look-back window that prevents chasing the same customer twice in the same week

Frequently asked questions

Will this email customers who have already paid?

No. The agent only looks at invoices that are still authorised and past their due date, and it skips any contact whose balance is offset by a credit note or overpayment in Xero.

How does the tone change as an invoice gets older?

The agent reads the age of the oldest overdue invoice for each customer. Up to 14 days late it sends a friendly nudge, 15 to 45 days it sends a firmer follow-up with the full statement, and 46 days or more it sends an escalation note and flags the account for human review in the Slack summary.

Can it chase the same customer every single morning?

No. Before drafting an email the agent checks whether that customer was already chased within the last few days and skips them if so. You can change the look-back window when you set it up.

Does it send the reminders from a shared inbox or from me?

Reminders are sent from the Gmail account you connect, so they look like a personal email from whoever owns that inbox. Connect a shared accounts-receivable inbox if you want them to come from the company.

What ends up in the Slack summary?

A single message every morning listing each customer that was emailed, the total amount being chased, and a callout for any accounts that hit the escalation threshold so a human can step in.