Guide

How to send an invoice: email, text or portal, step by step

Learn how to send an invoice by email, text or client portal: what to attach, subject line examples, the best time to send and how to follow up.

Updated Nov 5, 2026 · By PayToMe Editorial

Here is how to send an invoice: finish the document, save it as a PDF, and email it to the person who approves payments with a clear subject line, the due date and a way to pay. Send it the day the work is done. For small jobs, a text with a payment link also works. Follow up if you hear nothing in a few days.

Why how you send an invoice matters

An invoice that is correct but never read is the same as an invoice that was never sent. The route you choose decides who sees it, how quickly it reaches the person who can pay, and whether you have a record that it arrived. Most late payments do not come from clients who refuse to pay. They come from invoices that sat in a spam folder, went to the wrong contact or were forgotten about in a busy week.

Sending well takes about two extra minutes: picking the right recipient, writing a useful subject line and making payment easy. Those two minutes tend to be the cheapest way to shorten the time between finishing work and getting paid. If you are still building the document itself, read how to write an invoice first.

Email, text or portal: which to use

There are three common ways to deliver an invoice. Each fits a different situation.

Method	Best for	Strengths	Watch out for
Email with PDF	Most business clients, anything over a few hundred dollars	Easy to file and forward, works with every accounting system, leaves a written record	Spam filters, wrong recipient, buried in an inbox
Text message with link	Quick local jobs, consumers, repeat customers who already text you	Read within minutes, one tap to pay	Needs the client’s agreement, no formal record for accounting, link safety
Client portal or invoicing platform	Ongoing work, larger clients, teams with an accounts-payable process	Status tracking, reminders and payment in one place	The client must log in or trust a new system

You are not locked into one. A common pattern is an email to the accounts-payable contact with the PDF attached, plus a text to the person you work with day to day saying the invoice is on its way. For the text route, see how to send an invoice by text.

How to send an invoice, step by step

Check the invoice one last time. Confirm the client’s legal name, the invoice number, the due date and the total. A wrong detail is the most common reason an accounts-payable team sends an invoice back.
Save it as a PDF. Name the file clearly, such as Invoice-2026-014-Northwind-Coffee.pdf. A good file name helps the client find it later and helps you find your own copy.
Find the right recipient. Ask who handles payment. If the client has an accounts-payable address, use it, and copy your day-to-day contact. Sending only to the person you work with often means the invoice waits for them to forward it.
Write a clear subject line. Include the word invoice, your business name, the invoice number and the due date. Examples are below.
Write a short email body. Say what the invoice covers, the total, the due date and how to pay. Keep it to a few lines.
Add a way to pay. A payment link, bank transfer details or a mailing address for checks. The fewer steps between reading and paying, the better.
Send, then record it. Note the date and the recipient in your records so you know when to follow up.
Follow up on a schedule. A brief confirmation request after two or three business days, a reminder shortly before the due date, and a polite note when it passes. For templates, see past due invoice email.

Subject line examples

A subject line should work if it is the only thing the client reads. Use the facts they will search for later.

Standard: “Invoice 2026-014 from Maya Ortiz Design, due 9 November”
With the project: “Invoice 2026-014: Northwind Coffee brand project, due 9 Nov”
Deposit: “Deposit invoice 2026-015, kitchen remodel, due on receipt”
Reminder before due date: “Reminder: invoice 2026-014 due Friday”
Follow-up: “Did invoice 2026-014 reach the right person?”

Avoid cute or vague subject lines, all capitals and urgent-sounding words on a first send. They look like spam and they set the wrong tone with a client you plan to keep.

A short email you can adapt

Subject: Invoice 2026-014 from Maya Ortiz Design, due 9 November

Hi Sam,

Thanks again for the brand project. Attached is invoice 2026-014 for 1,501.38 USD, due on 9 November 2026. You can pay by bank transfer using the details on the invoice, or with the link below.

If this needs to go to your accounts-payable team, tell me who to send it to and I will do that. Please let me know if anything is unclear.

Best, Maya

Notice what it contains: the number, the amount, the due date, a payment route and an offer to redirect it. It does not apologize for asking to be paid, and it does not lecture.

When to send an invoice

Send it as soon as the work is done or the milestone is reached. For ongoing work, bill on the same day each week or month so the client learns your rhythm. For example, a monthly retainer that is invoiced on the first business day of every month will usually be processed in the same cycle each time.

A few timing rules help:

Same day or next business day is the target for one-off jobs. The due date normally runs from the invoice date, so a delay of a week is a week of lost cash.
Mid-week mornings are a reasonable choice for email, because messages sent late on Friday sit until Monday. This is a habit, not a rule, so test what works for your clients.
Before month end matters for clients that run payment batches. Ask when their payment run happens and aim to land before the cutoff.
Deposits first. If the agreement calls for a deposit, send that invoice before starting work.

Do I need to worry about email laws?

Invoices are usually transactional messages, but it is worth knowing the rule. The FTC’s CAN-SPAM guidance says a message whose primary purpose is transactional or relationship content, such as content that facilitates, completes or confirms a commercial transaction the recipient has already agreed to, is exempt from most of the law’s requirements. The FTC also says the categories are viewed narrowly, and that the law makes no exception for business-to-business email.

In practice that means: keep your invoice emails about the invoice, use an accurate “From” name and a subject line that reflects the content, and keep marketing out of them. If you add a promotion for another service, the message may count as commercial and carry more requirements. This is general information, not legal advice. For texts, see the consent points in how to send an invoice by text.

A worked example: one invoice, five touches

Maya finishes the Northwind Coffee brand project on Monday 26 October 2026. Her terms are Net 14. Here is her schedule.

None of these messages is aggressive. Each one gives the client an easy way to fix the situation, and each leaves a dated record. If a client does go quiet, the late fee calculator can help you work out any agreed fee before you mention it, and how to ask for payment covers the tone to use.

Mistakes to avoid when sending invoices

Sending to the wrong person. Your project contact may not be the approver. Ask who pays.
No subject line detail. “Invoice” alone is easy to lose among forty other messages.
Attaching a file the client cannot open. Use a PDF, not a proprietary format, and keep the file small.
Hiding the payment method inside the PDF only. Repeat the amount, due date and how to pay in the email body.
Sending from a no-reply address. Clients with questions need a human to answer.
Waiting for a “good moment.” There is no good moment to ask for money. The best moment is when the work is fresh.
Not keeping a record. Save the sent email or the delivery receipt. It is your evidence of when the invoice was issued.
Changing a sent invoice quietly. If something is wrong, send a corrected invoice or a credit note and say clearly that it replaces the earlier one.

Checklist before you press send

The invoice has the client’s correct legal name and billing details.
The invoice number is unique and the due date is a calendar date.
The PDF has a clear file name and opens correctly.
You are sending to the person who approves payment, with your day-to-day contact copied.
The subject line contains “invoice,” your name, the number and the due date.
The email body states the amount, the due date and how to pay.
A payment link or full payment instructions are included.
You have noted the send date and set reminders for follow-up.

Where PayToMe fits

The invoice generator is live today and makes a PDF you can attach to any email. In PayToMe, now in public beta, you can send invoices by email with a public invoice link where clients can pay online. Smart reminders are in development. Sign in to PayToMe to send your first invoice.

Sources

This is general information, not legal advice. The description of transactional messages, the narrow reading of the categories and the point that CAN-SPAM makes no exception for business-to-business email come from the FTC guide CAN-SPAM Act: A Compliance Guide for Business. Rules about email and text consent differ by country and state, so check your local rules if you send to clients abroad. The send schedule, subject lines and email text above are examples and suggestions, not legal requirements.

Frequently asked questions

Should I send an invoice as a PDF attachment or a link?

Either works, and many senders do both. A PDF is easy to file and forward to accounting. A payment link lets the client pay in one step. If you can only choose one, choose the one your client's finance team already uses. Ask once, then keep notes.

What should the subject line of an invoice email say?

Put the facts a busy person scans for: the word invoice, your business name, the invoice number and the due date. For example, "Invoice 2026-014 from Maya Ortiz Design, due 9 November." Avoid vague lines such as "Hello" or "Documents."

How soon after finishing the work should I send an invoice?

As soon as the work is done or the milestone is reached, ideally the same day or the next business day. The due date is usually counted from the invoice date, so every day you wait moves your payment back by a day.

Do I need to send invoices from a business email address?

It is not a legal rule, but it helps. A message from a name at your own domain looks more trustworthy than one from a free webmail address, and clients are more likely to open it and less likely to treat it as a scam.

Is it okay to send an invoice by text message?

It can be, if the client has agreed to receive texts from you and you include an easy way to opt out. Texting suits quick, small jobs. For larger invoices, also send an email so there is a record the client's accounting team can file.

How do I know the client received my invoice?

Ask for a quick confirmation in your email, or use a tool that shows when a message was opened. If you hear nothing within two or three business days, send a short follow-up asking whether it reached the right person.