Should you chase overdue invoices by phone, email, SMS or WhatsApp

When an invoice ticks past its due date, the first question is no longer if you should chase it, but how. Do you send a polite email that might get lost in a crowded inbox? Do you pick up the phone and risk an awkward conversation? Or do you try a more modern, direct approach like SMS or WhatsApp? The channel you choose can dramatically affect your chances of getting paid, the time you spend chasing, and the health of your client relationship.

This guide compares the main channels for chasing overdue B2B invoices in the UK—email, phone, SMS, and WhatsApp. We’ll break down the pros, cons, and professionalism of each, helping you build a credit control process that is both effective and maintains goodwill with your clients.

Why Your Choice of Chasing Channel Matters

For a small business or freelancer, effective credit control isn't just about administration; it's about survival. Consistent cash flow is the lifeblood of your business, and late payments directly threaten it. Your approach to chasing debt, however, is a delicate balancing act.

• Effectiveness: Some methods get faster results than others. A phone call is harder to ignore than an email.
• Time Investment: Manually chasing dozens of invoices is a huge drain on your time—time that could be spent on billable work or growing your business.
• Professionalism: The method you use reflects on your brand. What works for a friendly sole trader client you know well may be completely inappropriate for a large corporate organisation's accounts payable department.
• Record Keeping: If a payment dispute escalates, having a clear, documented trail of communication is essential. This is crucial if you ever need to invoke your rights under UK late payment legislation.

Choosing the right tool for the right situation is key. A £150 invoice that’s three days late requires a different touch to a £15,000 invoice that’s 45 days overdue.

The Workhorse: Chasing Invoices by Email

Email is the default method for B2B communication and, for most businesses, the foundation of their credit control process. It’s structured, professional, and provides a clear audit trail.

Pros of Using Email

• Creates a Written Record: This is email's single biggest advantage. Every email you send is automatically time-stamped, creating an undeniable record of when you sent reminders. This 'paper trail' is invaluable if you need to escalate to a formal letter before action or the small claims court.
• Professional Standard: In the UK business world, email is the expected channel for financial communications. It’s non-intrusive and respects the recipient's workflow, allowing them to deal with the request when they are at their desk.
• Scalability and Automation: You can create templates for different stages of the chasing process (e.g., polite reminder, firm reminder, final notice). Better still, this process can be fully automated. Tools like InvoiceReminder connect to your accounting software (like Xero or QuickBooks) and send these escalating reminders on your schedule, so you don't have to think about it.
• Allows for Attachments: You can—and always should—attach a PDF copy of the original invoice to every reminder. This instantly removes the common excuse of "we never received it" or "can you send it again?".

Cons of Using Email

• Easy to Ignore: Emails are easily deleted, archived, or simply lost in an overflowing inbox. A client under pressure may intentionally ignore payment reminders, and email makes this easy to do.
• Lacks Immediacy: Unlike a phone call, an email doesn't demand an instant response. It lacks the same psychological urgency.
• Can Be Impersonal: A generic, automated-sounding email can be easy to dismiss. While automation is efficient, the tone needs to be carefully crafted to sound human and reasonable, at least in the early stages.

Best Practices for Email Chasing

1. Use a Clear Subject Line: Don't be vague. Include the invoice number and your company name. For example: "Overdue Invoice INV-123 from Your Company Ltd".
2. Keep it Concise: Get straight to the point. State the invoice number, the amount due, and the due date.
3. Attach the Invoice: Always include the PDF. No exceptions.
4. Escalate the Tone: Your first reminder should be gentle and assume an honest mistake. Subsequent emails can become firmer, eventually referencing your right to add interest and compensation under UK law.

The Direct Approach: Chasing Invoices by Phone

When emails are met with silence, the phone is the logical next step. It’s a direct, human intervention that forces the issue into the open and is significantly harder for a client to ignore.

Pros of Using the Phone

• Immediate Feedback: A phone call cuts through the noise. You can quickly find out why the invoice hasn't been paid. Is it lost? Is it disputed? Is it approved and just waiting for the next payment run? This information is gold.
• Harder to Ignore: It’s much more difficult to fob someone off in a live conversation than it is to ignore an email. A call creates a moment of accountability.
• Personal Connection: A polite, professional phone call can actually strengthen a client relationship. It shows you are engaged and allows you to resolve issues collaboratively, rather than just sending sterile digital demands.

Cons of Using the Phone

• No Automatic Paper Trail: A phone conversation leaves no record unless you meticulously document it. If a client promises payment on a call and then fails to deliver, you have no proof of that agreement without a follow-up email.
• Extremely Time-Consuming: Finding the right person, leaving voicemails, and playing phone tag can consume hours of your day. For a business with many clients, chasing every overdue invoice by phone is simply not scalable.
• Can Be Confrontational: If you’re not a naturally confident caller, or if the client is defensive, the conversation can become awkward or even damaging to the relationship. It requires a specific skill set: staying calm, professional, and firm without being aggressive.
• Gatekeepers: In larger organisations, getting past a receptionist to the actual person in accounts payable who can authorise your payment can be a challenge in itself.

Best Practices for Phone Chasing

1. Be Prepared: Before you dial, have the invoice number, due date, amount, and a brief history of the reminders you’ve already sent.
2. Stay Calm and Objective: State the facts. "I'm calling about invoice 123, which was due on [Date]. We haven't received payment yet and I wanted to check everything is okay."
3. Identify the Right Contact: Your goal is to speak to Accounts Payable, not your day-to-day contact who may have no control over payments.
4. Agree on a Specific Action: Don't end the call with a vague "we'll look into it." Aim for a concrete commitment. "So, can I confirm you will process this for payment by this Friday?"
5. Follow Up Immediately: This is the most critical step. Send a short email straight after the call: "Hi [Name], thanks for the chat. As discussed, you've confirmed payment for invoice 123 will be made by [Date]. We look forward to receiving it." This creates the paper trail you need.

The Modern Nudge: Chasing Invoices by SMS & WhatsApp

Using text-based messaging like SMS or WhatsApp for invoice chasing is a relatively new and often debated tactic. It leverages the high open rates of these platforms but comes with significant risks to professionalism.

Pros of Using SMS/WhatsApp

• Extremely High Open Rates: Research consistently shows that SMS messages have open rates of over 95%, often within minutes of being received. Your message will be seen.
• Sense of Urgency: The instantaneous nature of a text or WhatsApp message can prompt a quick response, even if it’s just to say "Sorry, will sort this now."
• Convenience: It’s a low-effort way to send a quick nudge and can be useful for clients who are often away from their desks (e.g., tradespeople).

Cons of Using SMS/WhatsApp

• Professionalism Concerns: This is the major drawback. For most B2B transactions, especially with corporate clients or for high-value invoices, a WhatsApp message can feel overly familiar, unprofessional, and even intrusive. It can blur the line between a business relationship and a personal one.
• Poor for Record Keeping: While the message is saved on your phone, it’s not part of a standard business audit trail in the same way as email. It's also impractical for conveying all the necessary details like invoice numbers and amounts clearly.
• Privacy and GDPR: You must have explicit consent to contact a client on their personal number for business finance matters. Using a personal WhatsApp account for business communications can also create data privacy complications.

When Might SMS/WhatsApp Be Appropriate?

This channel should be used with extreme caution and only in specific scenarios:

• With Established, Informal Clients: If you have a long-standing, friendly relationship with a sole trader or very small business owner and your communication is already informal, a gentle text might be acceptable.
• As a Secondary Nudge: It should never be the first point of contact. A good use case is after an email and a phone call have gone unanswered. A simple SMS like: "Hi John, just a quick one - I've sent an email regarding our overdue invoice 123. Could you take a look when you get a moment? Thanks, [Your Name]." can work well.
• For Appointment Reminders, Not Debt: These channels are much better suited for service reminders than for chasing debt.

Never use SMS or WhatsApp to send a first reminder or to chase a client you don't know well. It's a quick way to appear unprofessional and damage your credibility.

Comparison Table: Choosing Your Chasing Channel

Channel	Professionalism	Record Keeping	Response Urgency	Time Investment (Manual)	Best For...
Email	High	Excellent	Low	Medium	Initial reminders, formal escalation, creating a legal paper trail, automation.
Phone	Medium-High	Poor (unless followed up)	High	High	Escalating when emails are ignored, understanding the reason for delay, getting a direct commitment.
SMS / WhatsApp	Low-Variable	Poor	Very High	Low	Quick, informal nudges to established clients after other methods have been tried. Not for first contact.

Building a Multi-Channel Chasing Strategy

The most successful credit control processes don't rely on a single channel. They use a logical, escalating sequence that starts gently and becomes progressively firmer. This "escalation ladder" approach is efficient and preserves client relationships by giving them every chance to pay before you take a more confrontational step.

Here is a best-practice timeline for a UK business:

1. Before Due Date (Optional): A polite "heads-up" email 3-5 days before the invoice is due can be a helpful, non-confrontational reminder.
2. Day 1-7 Overdue (Email): A friendly, automated reminder. The tone should assume an oversight. "Just a gentle reminder that invoice 123 is now due for payment." Attach the invoice.
3. Day 8-14 Overdue (Email): A second, slightly firmer email. "Following up on our previous email, invoice 123 is now 8 days overdue. Please let us know when we can expect payment." Attach the invoice again.
4. Day 15+ Overdue (Phone Call): If two emails have been ignored, it's time to pick up the phone. A direct conversation is now warranted. Follow up with an email summarising the call.
5. Day 21+ Overdue (SMS Nudge - Optional): If you can't reach them by phone, a quick SMS may be appropriate here for certain clients. "Hi [Name], tried calling about our overdue invoice. Please check your email and get in touch."
6. Day 30+ Overdue (Final Notice / Letter Before Action): This is the final formal step. Send a final email or a letter by post. This communication should be unambiguous. It should state the invoice is now 30 days overdue and that if payment is not received by a final deadline (e.g., in 7 days), you will add statutory interest and fixed-sum compensation as entitled under the Late Payment of Commercial Debts (Interest) Act 1998.

The Legal Bit: Your Rights Under the Late Payment Act

As a UK business supplying goods or services to another business, you have a statutory right to claim interest and compensation on late payments. This is not just something you can put in your contract; it's the law. Knowing your rights under the Late Payment of Commercial Debts (Interest) Act 1998 is a powerful tool in your final demands.

You are entitled to charge:

• Statutory Interest: This is 8% plus the Bank of England's base rate. The base rate changes, so you should always check the current rate on the Bank of England's website when calculating it.
• Fixed Sum Compensation: This is a one-off charge per invoice, designed to cover the cost of recovery. The amount depends on the size of the debt:
  • £40 for debts up to £999.99
  • £70 for debts from £1,000 to £9,999.99
  • £100 for debts of £10,000 or more

Simply referencing your intention to apply these charges in your final notice email is often enough to trigger an immediate payment from a reluctant client. It shows you are serious and aware of your legal rights. This is general guidance, not legal advice, and your specific contract terms may vary.

Frequently asked questions

Is it unprofessional to chase an invoice on its due date?

Yes, in most cases it is. Bacs payments in the UK can take a day or two to clear. Chasing on the exact due date can appear overly aggressive and suggests you don't trust your client. It's best practice to wait at least 2-3 business days after the due date before sending your first polite reminder.

Can I use WhatsApp to chase a large corporate client?

It's highly inadvisable. Large companies have structured accounts payable departments that operate exclusively via email and formal systems. A WhatsApp message would likely be seen as unprofessional, and it probably wouldn't even reach the person responsible for making the payment. Stick to email for all corporate clients.

What's the most important thing to include in a reminder email?

The invoice number, the amount, the due date, and a PDF copy of the original invoice. Attaching the invoice is crucial as it removes the common excuse of "I don't have it" or "can you resend it?", saving a whole cycle of communication.

Do I have to warn a client before adding late payment interest?

While it is your statutory right for B2B transactions, it is far better for your client relationship to warn them first. Best practice is to state clearly in your 'Final Notice' or 'Letter Before Action' that if payment is not made by a specific final deadline, you will then re-issue the invoice with the statutory charges added. This gives them one last chance to pay the original amount.

When should I consider using a debt collection agency?

This should be a last resort. An agency will take a significant percentage of the recovered debt, and their involvement will almost certainly terminate your relationship with that client. You should only consider this after your own comprehensive chasing process—multiple emails, phone calls, and a formal Letter Before Action citing the Late Payment Act—has completely failed.

Can I automate my invoice chasing?

Yes, you can and you should automate the email part of your chasing. Using software to send scheduled, escalating reminders is the single most efficient way to manage credit control. It ensures no overdue invoice is ever forgotten, saves you hours of manual work, and maintains a professional and consistent process for the crucial early stages of chasing.

Stop Chasing, Start Automating

Manually tracking and chasing overdue invoices is a time-consuming task that drains focus from your core business. A systematic, automated approach for your email reminders is the most effective way to improve cash flow and reduce administrative stress.

InvoiceReminder is built for UK small businesses, freelancers, and accountants who want to put their credit control on autopilot. It connects directly with Xero, FreeAgent, Sage, and QuickBooks to automatically chase your overdue invoices using customisable email schedules that escalate from friendly to firm. At no cost right now, the Free plan provides unlimited email reminders with no card required, making it easy to get started. For those needing more, paid plans add features like SMS reminders. InvoiceReminder is built by the team behind WeCovr, a company authorised and regulated by the Financial Conduct Authority which has arranged over one million insurance policies for UK customers.