How to Collect Unpaid Invoices: 7-Step Framework

Send a Friendly Reminder

The first contact should be warm and assume good faith. Most late invoices are not intentional — they result from AP inbox overload, approval bottlenecks, or simply being missed. Your goal is to resurface the invoice and make payment as easy as possible.

What to include: Invoice number, amount due, original due date, and a direct payment link. Attach the original invoice PDF. Address the person by first name, reference the specific project or PO number, and offer to help resolve any questions.

Real example: Acme Corp owes $4,750 for consulting services delivered in January, Net 30 terms. Invoice #2026-0142 was due February 15. On February 16, send: "Hi Sarah, just a quick note that invoice #2026-0142 for $4,750 was due yesterday. I've attached a copy — you can pay directly via the link below. Let me know if you have any questions."

Channel: Email. Keep it to 3-4 sentences. Subject line: "Invoice #2026-0142 from [Your Company] — Due Feb 15."

See our collection email writing guide for 5 proven templates at each stage.

Make Direct Phone Contact

If the email hasn't produced a response within 48 hours, pick up the phone. Phone calls get a 4-6x faster response than email alone, because they create real-time accountability and allow you to uncover the actual reason for non-payment on the spot.

What to say: "Hi Sarah, this is James from TechFlow Solutions. I'm calling about invoice #2026-0142 for $4,750 that was due on February 15. I just wanted to confirm you received it and see if there are any questions on your end." Keep it collaborative. You are helping them close an open item, not accusing them of wrongdoing.

Common responses and how to handle them:

• "I didn't receive the invoice." Resend immediately. Ask for the direct email of whoever processes payments. Follow up the same day with a "just resent" email.
• "It's in our approval queue." Ask for the expected approval date. Set a calendar reminder to follow up the day after that date.
• "We're having cash flow issues." Offer a payment plan. A partial payment now is better than a full payment never.
• "There's a dispute with the work." Escalate to your delivery team immediately. See our dispute resolution guide.

Send a Formal Past-Due Notice

If the friendly reminder and phone call haven't resolved things, shift your tone from casual to professional. This email serves as a formal record that the account is past due and introduces the concept of consequences.

Key elements: Reference both previous contacts (the email on Feb 16 and the call on Feb 19). State the total amount due including any late fees per your contract. Mention your payment terms clearly. Provide a specific deadline: "Please remit payment by March 1, 2026."

Real example: "Dear Sarah, this is a formal notice that invoice #2026-0142 for $4,750, originally due February 15, remains unpaid. Per our service agreement (Section 8.2), a 1.5% monthly late fee applies to balances past 15 days. The current balance is $4,821.25. Please remit payment by March 1 to avoid further escalation."

Important: Always CC the AP department email (accounts-payable@ or ap@) if available. Many companies have dedicated AP teams that process payments independently from your day-to-day contact. Your contact may have forwarded the original invoice, but it got lost in AP's queue.

Escalate to a Senior Contact

When your primary contact cannot or will not resolve the invoice, go higher. Contact the CFO, VP of Finance, or business owner directly. Senior executives have the authority to push payments through immediately, and they typically care deeply about vendor relationships and credit reputation.

Finding the right person: Check LinkedIn for the CFO or Controller title. Use your CRM notes for any executive contacts from the sales process. If the company is small (under 50 employees), go directly to the CEO or owner.

Real example: For the $4,750 Acme Corp invoice, you'd email the CFO: "Dear Michael, I'm reaching out regarding an outstanding invoice (#2026-0142, $4,821.25) with your company. I've been working with Sarah Chen on your team since February 15, but we haven't been able to resolve this. I'd appreciate your help in getting this to the right person for payment processing."

This works because: Executives are embarrassed when vendors have to escalate. 68% of invoices escalated to a C-level contact are paid within 5 business days. The key is to be respectful and solution-oriented, never threatening.

Issue a Final Demand Letter

A demand letter is a formal written notice that serves as the last step before third-party involvement. It should be sent on company letterhead (or as a PDF attachment) and clearly state the consequences of continued non-payment.

What a strong demand letter includes:

• Complete account history: Original invoice date, amount, services delivered, all previous contact attempts with dates
• Total amount owed: Including late fees, interest, and any administrative charges per your contract
• Clear deadline: "Payment must be received by April 1, 2026" — give exactly 10 business days
• Consequences: "If payment is not received, we will refer this account to our collection partner and may pursue legal remedies available under the contract"
• Payment instructions: Bank wire details, online payment link, check mailing address

For the Acme example: The demand letter would show $4,821.25 (principal + late fees), reference all 4 previous contact attempts, and set a payment deadline of April 1. Roughly 40% of accounts respond to a demand letter, making it a high-ROI step before incurring third-party costs.

Engage a Collection Agent or Agency

When internal efforts have been exhausted, it is time to bring in a specialist. You have three main options, each with different cost structures and recovery rates.

When to use each: Traditional agencies work best for high-volume consumer debt. AI collection agents (like AgentCollect) are ideal for B2B invoices where you want to preserve the client relationship — the AI handles calls and emails professionally, at a fraction of the cost. Attorneys are best when the debtor is unresponsive and the amount justifies legal costs (typically $10,000+).

Read our full guide to sending accounts to collections for a detailed decision tree and ROI calculation framework.

Pursue Legal Action

Legal action is the last resort and should only be pursued when the amount justifies the cost and the debtor has assets to recover against. For the Acme Corp $4,750 example, small claims court (limit varies by state, typically $5,000-$25,000) is the most cost-effective legal path.

Legal options by amount:

• Under $5,000: Small claims court. Filing fees $30-$200. No attorney required. Process takes 30-60 days.
• $5,000-$75,000: State court civil lawsuit. Attorney fees typically $3,000-$10,000 or 33% contingency. Process takes 6-18 months.
• Over $75,000: Federal court (if diversity jurisdiction applies) or state court. Attorney required. Budget $10,000-$50,000+ in legal fees.
• International debts: Significantly more complex. Consider arbitration clauses in future contracts. Collection agencies with international reach are often more practical than litigation.

Before filing: Verify the debtor is still in business (check state business registry). Confirm they have collectible assets. Calculate whether the expected recovery minus legal costs exceeds the write-off tax benefit of the bad debt. For the $4,750 Acme invoice, small claims court at $100 filing fee is a clear yes. For a $3,000 invoice requiring a $5,000 attorney, the math does not work.