Best way to follow up on unpaid invoices
Researched and Written by Bhargav Moturi
Reviewed and Edited by RajAn effective way to follow up on unpaid invoices is to implement sequential outreach after their due dates have passed, escalating in tone, as the payments remain overdue. For maximum impact, you can utilize different channels to send reminders, including email, phone, and text.
Sending structured invoice reminders helps your business improve cash flow by reducing late payments while maintaining positive relationships with your customers.
We have all experienced it: Complete silence or a delayed response after sending an invoice to your customer who hired your service/product.
Days turn into weeks, yet the payment remains unpaid.
Frustrating, right?
Chasing late payments is essential to protect your business’s financial stability and operational cash flow. It automatically keeps other areas in check, such as vendor payments, timely payroll, and investments.
This is why it becomes essential for you to learn how to follow up on overdue invoices. Our blog dives deep into the best payment follow-up strategies for quickly recovering outstanding amounts from your customers. It also includes effective reminder templates that you can use to get started.
Best way to follow up on unpaid invoices
Have you been only emailing customers for accounts receivable follow-ups?
Relying exclusively on email is a common reason your invoices remain unpaid, even after multiple reminder emails.
One of the best ways to follow up on overdue invoices is to integrate multiple communication channels. It helps create a sense of urgency and boosts visibility.
Let’s look at why relying only on email does not work:
- Spam filters & deliverability issues: Many emails fail to land in a user’s main inbox. They often get buried in the promotional tab or marked as spam by their email service provider.
- Inbox overload: Your customers receive tens of emails daily. Your payment reminder email can easily be ignored with the intention of handling it later, which unfortunately does not happen.
- Staff turnover & absences: If the point of contact in the customer’s AP department is unavailable, your invoice may remain unpaid or unread for a long period of time.
To reduce late payments and maximize response rates, vary your communication channels as the payment timeline progresses. Include emails, phone calls, text SMS, and even WhatsApp in your outreach. This allows your message to reach the right decision-maker and receive the priority attention it deserves.
Ensure your reminder message has all the essential details
You’ve learnt that a combination of different communication channels offers a quick resolution to unpaid invoices.
But whether you’re just starting the outreach or already in the middle of the sequence, aim for no more than one reminder a day.
To improve its effectiveness, the best practice is to ensure the content is accurate and complete.
Try to include these three essential details in every follow-up message. They help eliminate the administrative friction for your customers, increasing chances of faster payments:
- Explicit reference data: Make sure you clearly state the invoice number, original due date, and payment due amount. If it is an email, you must mention these details in both the subject and the body.
- Payment link: Include the online payment link along with instructions, if any. Double-check that the link opens and takes the user to the payment page. It should not show any errors, such as ‘page not found’.
- Call to Action (CTA): After you provide the invoice overdue information, end the message with a clear CTA: make payment.
Follow-up email and text (SMS) sequences and ready-to-use templates
Email templates
1) Day 3 past due: Friendly & supportive
Subject: Friendly Reminder: Invoice #{{invoiceNumber}} Due Soon
Body: Dear {{customerName}},
I’m reaching out to remind you that invoice number {{invoiceNumber}} for the period of {{invoicePeriod}} was due on {{dueDate}}. The total amount due is {{invoiceAmount}}. We appreciate your prompt attention to this matter.
For more information, feel free to check out this link: Pending Payment Details.
We look forward to your swift action to settle this invoice. Thank you for your cooperation!
Best Regards,
{{Sender’s name}}
Company’s name
2) Day 5 past due: Clear & professional
Subject: Invoice #{{invoiceNumber}} due date passed: Payment Reminder
Body: Dear {{customerName}},
This is a friendly reminder that your invoice #{{invoiceNumber}} for the period of {{invoicePeriod}} is nearing its due date on {{dueDate}}. The outstanding balance is {{invoiceAmount}}.
Please visit the link for payment details: Pending Payment Details.
Your prompt payment is greatly appreciated to avoid late fees. Thank you for your attention, and we’re here to assist if you have any queries!
Best Regards,
{{Sender’s name}}
Company’s name
3) Day 7 past due: Direct & administrative
Subject: Action Required: Payment for Invoice #{{invoiceNumber}}
Body: Dear {{customerName}},
I hope this message finds you well. We wanted to remind you that invoice number {{invoiceNumber}}, covering the period of {{invoicePeriod}}, is due on {{dueDate}} with an outstanding amount of {{invoiceAmount}}.
Please take a moment to review the invoice by following this link: Pending Payment Details.
Your timely response is essential, and we appreciate your cooperation in resolving this matter quickly.
Best Regards,
{{Sender’s name}}
Company’s name
4) Day 10 past due: Urgent & direct
Subject: Urgent: Invoice #{{invoiceNumber}} Payment Reminder
Body: Dear {{customerName}},
We wanted to kindly remind you about the outstanding invoice {{invoiceNumber}} for the period of {{invoicePeriod}}. The total amount due is {{invoiceAmount}}, with a due date of {{dueDate}}. For your convenience, you can view the details and make the payment at your earliest convenience here: {{paymentInvoiceLink}}.
Please let us know if you have any questions. Your prompt action will be highly appreciated!
Best Regards,
{{Sender’s name}}
Company’s name
5) Day 15 past due: Formal & authoritative
Subject: Overdue Reminder: Action Required
Body: Dear {{customerName}},
This is a gentle reminder regarding your invoice {{invoiceNumber}} for the duration of {{invoicePeriod}}. As of now, the invoice amount of {{invoiceAmount}} is overdue and was due on {{dueDate}}. To avoid any inconvenience, please take a moment to settle it through this link: {{paymentInvoiceLink}}.
Best Regards,
{{Sender’s name}}
Company’s name
SMS templates for unpaid invoices
1) Hi {{customerName}}, this is a reminder about your pending invoice {{invoiceNumber}} for the period {{invoicePeriod}}. The due amount is {{invoiceAmount}}, due by {{dueDate}}. Please settle it promptly. More details: {{goalURL}}
2) Hi {{customerName}}, just a friendly nudge about invoice {{invoiceNumber}} from {{invoicePeriod}}. The total due is {{invoiceAmount}} by {{dueDate}}. Kindly check: {{goalURL}}
3) Hi {{customerName}}, we noticed invoice {{invoiceNumber}} from {{invoicePeriod}} has yet to be settled. The amount of {{invoiceAmount}} is due on {{dueDate}}. Please review: {{goalURL}}
4) Hi {{customerName}}! This is a reminder for Invoice #{{invoiceNumber}} for the period of {{invoicePeriod}}. The amount of {{invoiceAmount}} is due by {{dueDate}}. Please pay ASAP!
5) Hi {{customerName}}! We wanted to remind you about Invoice #{{invoiceNumber}} from {{invoicePeriod}}. It totals {{invoiceAmount}} and is due on {{dueDate}}. Thank you for taking care of this!
Conclusion: Automating your accounts receivable with AI
Mastering how to follow up on overdue invoices is essential for maintaining steady cash flow and keeping your business financially healthy. However, manually tracking past-due accounts, sending multi-stage follow-up emails, and making phone calls consumes valuable time that finance teams could spend on strategic planning.
To eliminate manual payment chasing entirely, you can deploy an autonomous AI AR Collections Specialist It acts as your digital team member, managing accounts receivable end-to-end. Here’s how it works:
- Seamless integration: The AI agent syncs with your existing accounting software, ERPs, and CRMs (such as QuickBooks, Xero, NetSuite, and HubSpot). All you need to do is authorize the integration.
- Automated multi-channel execution: It initiates timely, personalized outreach across email, text, phone calls, and WhatsApp. Each message follows your uploaded collections playbook, reaching decision-makers on their preferred channel.
- Routes and resolves customer queries: The platform tries to resolve incoming questions on its own and routes live calls to your human staff based on escalation rules defined in your playbook.
Using AI is a great way to follow up on your pending payments. These platforms help finance teams reduce late payments, lower Days Sales Outstanding (DSO), and collect receivables faster than simple, generic reminders. Request demo to see how to integrate a modern AI AR Collections agent to your finance system and automate your collections!
Frequently Asked Questions (FAQs)
When emails remain unanswered after 7 to 10 days, switch communication channels immediately. Pick up the phone and call your primary client contact or their finance department directly. Email messages are easily overlooked or filtered, whereas a short, polite phone conversation usually resolves miscommunication or administrative hold-ups in minutes.
Yes, provided that late fee policies were explicitly detailed in your original client agreement, contract, or proposal terms. Always disclose late fee schedules on original invoices to make enforcement transparent and legal.
Every follow-up email or message should feature the invoice number, original due date, and exact balance in both the subject line and body text. Always attach a PDF copy of the invoice and provide a direct, one-click online payment link to eliminate administrative friction for the finance team.
An AI AR Collections Specialist automates overdue invoice chasing by integrating directly with your ERP or accounting software. The AI agent executes personalized, multi-channel outreach across email, SMS, and voice calls, referencing specific invoice details, handling customer payment inquiries in real time, and updating collection statuses on a unified dashboard.
No. Modern AI AR collections agents are designed to communicate courteously and professionally, mirroring human AR representatives while maintaining high brand standards. The agent follows your uploaded finance playbook to curate outreach scripts and maintains a gentle, professional tone to ensure client goodwill remains intact.