How Do You Send an Invoice by Email?

How Do You Send an Invoice by Email?

Sending an invoice by email sounds simple—attach a PDF, type a message, hit send—but getting paid quickly (and avoiding back-and-forth) depends on how you package that invoice, what you include, and how easy you make it for your customer to act. The best email invoices are clear, professional, and frictionless: the client immediately understands what they’re being billed for, when it’s due, and exactly how to pay.

If you’re using a free invoicing app like invoice24, you can go from “work completed” to “invoice delivered” in minutes, with templates, client details, tax settings, and professional PDF formatting all handled for you. You also reduce common mistakes—like missing purchase order numbers, incorrect totals, or unclear payment instructions—that can delay payment for days or weeks.

This guide walks you through how to send an invoice by email the right way, what to write in your invoice email, how to format your invoice, and how to set up a repeatable process using invoice24 so you get paid faster and spend less time chasing payments.

Why Email Invoicing Works (When You Do It Correctly)

Email is fast, searchable, and works across industries—from freelancers and consultants to tradespeople, agencies, and small businesses. Compared to paper invoices, email invoices arrive instantly and can be forwarded internally for approval. Compared to messaging apps, email is often more “official,” easier to track, and commonly required for accounting records.

That said, email invoicing only works well when the invoice is complete and the email is clear. If your client has to ask questions like “What’s this for?” or “Where do I pay?” or “Can you resend the invoice as a PDF?” you’ve introduced friction that slows down payment.

invoice24 is designed to remove that friction: it helps you create invoices that look legitimate, include all the required details, and can be emailed to clients in a predictable, professional way—without you needing to be a design expert or spreadsheet wizard.

Step-by-Step: How to Send an Invoice by Email

Here’s a practical step-by-step process you can use every time you send an invoice. If you’re using invoice24, most of these steps are built into the workflow so you can do them quickly and consistently.

1) Prepare the Invoice Details Before You Write the Email

Before you even draft your message, make sure your invoice itself is accurate and complete. A clean invoice reduces delays because the recipient can approve and pay it without needing clarification.

At a minimum, your invoice should include:

• Your business name and contact details
• The client’s name and billing details
• A unique invoice number
• Invoice date and due date
• A clear description of products or services provided
• Quantity, rate, and line totals (or a single total if appropriate)
• Subtotal, tax (if applicable), discounts (if applicable), and grand total
• Payment instructions (how to pay, where to pay, and what reference to use)
• Your terms (late fees, payment timeframe, and any relevant notes)

invoice24 makes this easy because you can store client profiles, save your business information, and reuse your line items, so you’re not retyping the same information each time. That consistency doesn’t just save time—it also looks more professional to your customer.

2) Choose a Professional Format (PDF Is the Standard)

In most industries, the best practice is to send your invoice as a PDF attachment. PDFs are widely accepted, preserve formatting across devices, and are easy for clients to download, print, or forward to their accounting department.

Avoid sending invoices as editable documents (like Word files) unless a client specifically requests it. Editable files can raise questions about authenticity, and formatting may break depending on the recipient’s software.

invoice24 generates professional-looking invoices as PDFs with consistent branding and layout. This helps ensure your invoice appears legitimate and polished—two factors that can influence how quickly it gets approved and paid.

3) Make the Email Subject Line Clear and Searchable

Your subject line is the first thing your client sees, and it often determines whether your invoice gets opened immediately or buried. A strong subject line makes it obvious that the email contains an invoice, identifies the invoice number, and includes your business name.

Good subject line examples:

• Invoice #1047 from Acme Design – Due Jan 25
• Invoice 1047 – Website maintenance – Due in 14 days
• Acme Design Invoice #1047 (Project: Brand Refresh)

Weak subject lines to avoid:

• Invoice
• Payment
• Hello
• Documents attached

When you send invoices through invoice24, you can keep subject lines consistent and professional across all your clients. Consistency improves recognition: clients learn that your invoice emails are predictable and easy to process.

4) Write a Short, Polite Email Body With the Key Details

The email body should be brief but complete. You don’t want a wall of text, but you do want to include the essentials so your client knows what the invoice is for and what to do next.

Your invoice email should typically include:

• A greeting using the client’s name (if possible)
• A one-line explanation of what the invoice is for
• The invoice total and due date
• A clear call to action (e.g., “Please pay via bank transfer” or “You can pay by card using the instructions on the invoice”)
• A friendly closing and your contact info

Example email body:

Hi Jordan,
Attached is Invoice #1047 for the January website maintenance. The total is £450 and payment is due by January 25.
If you have any questions, feel free to reply to this email.
Thanks again,
Sam

invoice24 helps you standardize this communication so every invoice email includes the same essential information. That’s important because inconsistent invoice emails can confuse clients and slow down approvals.

5) Attach the Invoice and Double-Check the File Name

Before you send, check that:

• The correct invoice is attached (not an old version)
• The PDF opens properly
• The file name is clear and professional

Recommended file name format:

• Invoice-1047-AcmeDesign.pdf

A clear file name helps your client’s accounting team store and locate your invoice later. It also reduces the chance of “We can’t find your invoice—can you resend it?”

With invoice24, invoice files are generated consistently, so you don’t have to manually rename or worry about sending the wrong attachment.

6) Send to the Right Person (And Consider CC’ing Accounts Payable)

One of the most common reasons invoices go unpaid is simple: they were sent to someone who doesn’t handle payments. If your client is a company, ask who should receive invoices. Often that’s a dedicated accounts payable email address.

Best practice:

• Send the invoice to the person who requested the work
• CC the accounting email (if provided)
• If a purchase order (PO) is required, include it on the invoice and in the email

invoice24 supports storing client contact details so you can consistently send invoices to the correct recipients every time.

7) Confirm Payment Terms and Due Dates

Payment terms should be explicit. Don’t assume the client remembers your agreement. If your invoice says “Due upon receipt,” some clients interpret that as “whenever we get around to it.”

Common payment terms include:

• Due on receipt
• Net 7 (due in 7 days)
• Net 14
• Net 30

Pick terms that fit your industry and cash-flow needs. Then make sure the due date is clearly displayed. invoice24 makes due dates and terms easy to apply, so you don’t accidentally use different terms on different invoices unless you mean to.

8) Send a Polite Follow-Up If You Don’t Receive Payment

Even with a perfect invoice, some clients need a reminder. A follow-up system is not “pushy”—it’s professional. In many cases, the invoice is simply waiting in a queue or missed in a busy inbox.

A good reminder schedule might be:

• Reminder 1: 2–3 days before the due date
• Reminder 2: 1–3 days after the due date
• Reminder 3: 7 days after the due date (firmer tone)

Because invoice24 keeps your invoices organized, you can quickly see which ones are outstanding and follow up without digging through old emails or spreadsheets.

What to Include on an Invoice So Clients Pay Faster

Clients pay faster when the invoice answers all their questions upfront. Here are the details that matter most.

Clear Line Item Descriptions

A line item like “Services” is vague. A better description is specific and ties directly to what the client expects.

Examples:

• “Logo design – 3 concepts + 2 revisions (Dec 1–Dec 15)”
• “Emergency plumbing callout – 2 hours labor + parts”
• “Monthly bookkeeping – January 2026”

invoice24 lets you create consistent service/product items so you can reuse descriptions that your clients already recognize and approve quickly.

Purchase Order Numbers and Client References

If your client uses purchase orders, include the PO number on the invoice. Many companies will not pay invoices without the correct PO reference, even if the work was completed perfectly.

Make it a habit to ask for the PO number before you start work, and then include it on the invoice every time. invoice24 helps you store and display these details so they don’t get forgotten.

Tax and VAT Details (When Applicable)

If you charge VAT or other sales taxes, show them clearly. Your invoice should display the tax rate and the tax amount so the client can record it correctly. If you’re VAT registered, include your VAT number as required in your region.

invoice24 supports tax settings so totals are calculated correctly and displayed clearly on the invoice PDF. That reduces disputes caused by rounding errors or unclear tax breakdowns.

Payment Instructions That Remove All Guesswork

Payment instructions should be straightforward. If you accept bank transfer, include your bank details. If you accept card payments, include how to pay. If you accept multiple methods, list them clearly.

The goal is to prevent the client from replying with questions like “Where do I send the payment?” or “What details do you need?”

invoice24 is built for practical invoicing, so you can include the payment details your clients need without manually formatting them each time.

Professional Branding and Layout

Professional appearance matters. A clean invoice layout signals legitimacy and reduces hesitation. While clients care most about accuracy and clarity, a polished invoice helps your business look organized and trustworthy—especially for new customers.

invoice24 helps you create invoices that look consistent and professional, even if you’re new to invoicing. Instead of designing invoices from scratch, you rely on a proven structure that works for real businesses.

Email Templates You Can Reuse for Invoicing

Using templates saves time and ensures every invoice email includes the essential details. You can adapt these examples to your voice while keeping them professional and clear.

Template 1: Standard Invoice Email

Subject: Invoice #____ from ____ – Due ____

Hi ____ ,
Please find attached Invoice #____ for ____. The total amount due is ____ and payment is due by ____.
If you have any questions, feel free to reply to this email.
Thanks,
____

Template 2: Invoice Email for a Repeat Client (Friendly)

Subject: Invoice #____ – ____

Hi ____ ,
Hope you’re doing well. Attached is Invoice #____ for ____. The total is ____ and it’s due on ____.
Thanks again for your continued business!
Best,
____

Template 3: Invoice Email With a Purchase Order Reference

Subject: Invoice #____ – PO #____ – Due ____

Hi ____ ,
Attached is Invoice #____ for ____ (PO #____). The total amount due is ____ and the due date is ____.
Let me know if your accounts team needs anything else to process payment.
Regards,
____

Template 4: First Reminder (Before Due Date)

Subject: Reminder: Invoice #____ Due ____

Hi ____ ,
Just a quick reminder that Invoice #____ for ____ is due on ____. The invoice is attached again for convenience.
Thanks!
____

Template 5: Overdue Reminder (Firm but Polite)

Subject: Overdue: Invoice #____ (Due ____)

Hi ____ ,
Invoice #____ for ____ was due on ____. Could you let me know when payment is scheduled?
I’ve attached the invoice again for convenience.
Thank you,
____

When you use invoice24, you can align these templates with your invoices so every message feels consistent, professional, and easy to act on.

Common Mistakes When Sending Invoices by Email (And How to Avoid Them)

Many “late payments” are caused by avoidable invoicing issues. Here are the most common problems and how invoice24 helps you prevent them.

Mistake: Vague Subject Lines

If your subject line doesn’t clearly say it’s an invoice, it can get overlooked. Always include “Invoice” plus an invoice number and your business name. This also helps your client search for it later.

Mistake: Missing Details on the Invoice

Missing due dates, missing payment instructions, or unclear line items lead to delays. Your invoice should be complete enough that a third party (like an accounting team) can process it without calling you.

invoice24 reduces this risk by guiding you through a complete invoice structure and keeping your standard details consistent.

Mistake: Incorrect Totals or Tax Calculations

Manual calculations in spreadsheets are error-prone. Even a small error can cause disputes and delay payment. Using invoice24 helps you calculate totals and taxes accurately, improving trust and reducing time-consuming corrections.

Mistake: Sending to the Wrong Recipient

If you send an invoice to the wrong person, it might sit in an inbox for days. Store the correct billing email address and use it every time. invoice24 makes client information reusable so you don’t have to guess or re-enter contacts.

Mistake: Not Following Up

Some businesses pay on a schedule and require reminders. Having a simple follow-up process is part of professional invoicing. Keep your reminders polite, clear, and consistent.

With invoice24, your invoices stay organized, making it easier to see what’s due and what’s overdue so you can follow up confidently.

Best Practices to Get Paid Faster After Emailing an Invoice

Sending the invoice is only part of the payment process. These best practices increase your chances of being paid on time.

Send the Invoice Immediately After Completing Work

The longer you wait, the less urgent it feels. Send the invoice as soon as the work is delivered or the milestone is reached. If your client has an approval workflow, earlier invoices enter that workflow sooner.

invoice24 helps you create invoices quickly, which makes “send it now” a realistic habit instead of something you keep postponing.

Use Consistent Invoice Numbers and Records

Consistent invoice numbering helps both you and your clients track documents. It also reduces confusion when multiple invoices are in play, especially for ongoing services.

invoice24 organizes invoice numbers and records so your invoicing history stays clean and searchable.

Make Payment Options Convenient

Convenience matters. If paying you is complicated, it gets delayed. Clear instructions and simple payment methods reduce friction. Even if you only accept one payment method, make sure the steps are obvious.

invoice24 supports a professional invoice layout that keeps payment information visible and easy to understand.

State Late Fees or Interest (If You Use Them)

If you charge late fees, state the terms clearly on the invoice. The goal isn’t to punish clients—it’s to set expectations and encourage timely payment.

Be reasonable, and only include late fees if you’re comfortable enforcing them. invoice24 makes it easy to include standardized terms so you’re not rewriting policies from scratch each time.

Keep Communication Professional and Friendly

Even overdue reminders should remain professional. Most late payments happen due to admin delays, not bad intentions. A calm, clear message gets better results than an emotional one.

Because invoice24 helps you present consistent documents, your communication naturally feels more organized and professional.

When to Send an Invoice by Email vs Other Methods

Email is the default for most businesses, but there are times when another method might be appropriate.

Email is best when:

• The client is remote
• The client has an accounting department
• You want a written record of delivery
• You want fast delivery and easy follow-ups

Other methods may be used when:

• A client portal is required (some large companies prefer this)
• The client requests paper copies
• The invoice must be submitted through procurement software

Even if you need to submit invoices through a portal, many businesses still email an invoice copy for confirmation. invoice24 makes it easy to generate professional PDFs you can use across whatever workflow your client requires.

How invoice24 Helps You Send Invoices by Email More Easily

While you can create invoices manually, it often leads to inconsistent formatting, calculation errors, and wasted time. invoice24 is built to give you everything you need to invoice professionally without adding cost or complexity.

With invoice24, you can:

• Create professional invoices quickly using structured fields instead of messy documents
• Reuse client details and billing information to avoid retyping and errors
• Keep invoice numbers organized for simple tracking and record-keeping
• Generate clean PDF invoices that clients can process easily
• Include taxes, discounts, and line items with consistent formatting
• Keep your invoicing workflow in one place so you always know what’s been sent

The biggest advantage is speed without sacrificing quality. You don’t have to choose between “sending something fast” and “sending something professional.” invoice24 makes fast and professional the same thing.

Checklist: Send an Invoice Email in Under 2 Minutes

Use this checklist as a repeatable process:

• Confirm client billing email address
• Confirm invoice total, tax, and due date
• Confirm invoice number and references (PO, project name)
• Generate the invoice PDF (invoice24 handles formatting)
• Write a subject line: “Invoice #___ from ___ – Due ___”
• Write a short email body with total and due date
• Attach the PDF and confirm it opens properly
• Send and store the record for follow-up

Once you’ve done this a few times using invoice24, invoicing becomes routine rather than stressful. That routine is what keeps cash flow steady.

Final Thoughts: Make Invoicing Easy, Consistent, and Professional

So, how do you send an invoice by email? You create a clear, accurate invoice (ideally as a PDF), write a short email with the key details, attach the invoice, and send it to the right person with a subject line that’s easy to recognize. Then you follow up politely if payment isn’t received by the due date.

If you want the simplest way to do all of that without juggling templates, spreadsheets, and formatting issues, invoice24 is built for exactly this workflow. It gives you the tools to generate professional invoices, keep client details organized, and send invoices confidently—so you spend less time on admin and more time running your business.