Invoice + AR followup automation.

For each open invoice, calculate days past due based on payment terms (net-30, net-60, net-90 — varies by customer contract). Net amount, currency, and payment terms pulled from the billing system. Prior-touch history pulled from the AR followup table — when was the last reminder sent, did anyone reply, what was the response. Without this history, you'd send the same nudge twice.

Customer's CRM record, contract value, payment history (do they pay on time historically, or do they always pay late?), recent support tickets, recent NPS, account owner. A first-time-late customer with a clean 24-month history needs a different touch than a chronic late-payer. The customer health monitor automation feeds risk signals here too — at-risk accounts get gentler outreach so AR doesn't accelerate churn.

3 days before due date, send a friendly reminder with the invoice attached, payment link, and any auto-pay setup if available. This catches the "just forgot to schedule it" cases that account for 30–40% of late payments. No urgency, no escalation language — just a courteous nudge with the click-to-pay path made easy.

On the due date, if the customer has a payment method on file and auto-pay is enabled, charge automatically. If the charge succeeds, invoice marked paid; sequence ends. If the charge fails (insufficient funds, expired card), customer routes immediately into the early lane with a payment-failed notification. Auto-charge converts ~50% of subscriptions silently — no email, no admin work.

Day-1 nudge, day-7 followup. AI-personalized — references the customer name, the specific invoice, and the easy-pay link. Never accusatory at this tier. The most common reason for early lateness is operational, not financial — the AP person was on PTO, the approval chain is slow, the invoice ended up in someone's spam folder. Friendly tone preserves the relationship.

If the invoice is still unpaid at day 10, the AE or CSM gets cc'd on the next followup so they can drop a friendly text or Slack to their primary contact. Most of the time the relationship-side ping resolves it — "hey, just checking, did your AP team see the invoice?" works better than a fifth automated email. CRM activity logs the cc so the rep knows.

Day-15 firmer email referencing the contract terms and the specific overdue amount. AE/CSM gets a Slack alert with the customer context and a "schedule a payment call" CRM task. The AE picks up the phone — automated email at this tier alone doesn't move the needle. The conversation often surfaces the actual blocker (PO needs reissuing, dispute on a line item, change of AP contact).

Day-30 notice that service may be paused if payment isn't received in the next 15 days, per contract terms. CFO or finance lead gets cc'd on the customer side. Internal Slack alert escalates to the CSM lead. The threat of service suspension is real but the language stays professional — burning the relationship over a $5K invoice loses you a $50K renewal next year.

At day 45, service is paused per contract (or, for non-paused service models, the account moves to "delinquent" status that blocks expansion or new contracts). The finance lead schedules a direct call with the customer's CFO or AP lead. AE pulled into the loop to manage the relationship side. The goal at this stage is recovery, not just collection — a customer at 45 days late is also a customer that's likely to churn unless you resolve it.

Two outcomes at this tier. Either the customer agrees to a payment plan — finance creates the schedule, the invoice splits into installments tracked separately, the relationship survives. Or the invoice gets written off, account marked closed-uncollected, and the customer goes to a third-party collections partner. The decision threshold is usually account-size and historical-relationship: a $200K-ARR customer rarely gets written off; a $2K cold-procurement customer often does.

Invoice still unpaid. Loops back to tomorrow's daily run, where it will be re-evaluated by aging tier — typically advancing by one day past due. If the days-late threshold has crossed into the next tier (e.g., from 14 to 15 days), the invoice moves into the new tier's lane on the next run. Final disposition (written off, payment plan, paid in full) only happens via the critical-tier pathway.