How to Send an Invoice (Email Templates & Best Practices)

Sending Is Where Most Invoices Go Wrong

Writing the invoice is half the job. The other half — the part people skip — is sending it properly. A perfectly formatted invoice sent to the wrong email address, with a vague subject line, buried in a thread about something else, will sit unpaid for weeks.

I've watched freelancers lose thousands to sloppy sending habits. The invoice was correct; the delivery was not. Wrong contact, no PDF attachment, subject line that said "invoice" and nothing else. The AP clerk at the client's company processes 200 invoices a month. Yours needs to be immediately identifiable and effortless to act on.

This guide covers the mechanics: who to send to, what to write in the email, how to format the subject line, what to attach, and how to follow up when nobody responds.

Before You Hit Send: A Quick Checklist

Run through these before every invoice email. It takes 60 seconds and prevents the most common delays:

Subject Lines That Don't Get Buried

Your subject line needs to do one thing: make it obvious this is an invoice that requires action. AP teams scan subject lines all day. Give them the key details upfront.

Examples that work:

Examples that don't:

Keep it under 60 characters if you can. Many email clients truncate longer subjects on mobile.

Email Templates You Can Copy

Three templates for different situations. Adjust the tone to match your client relationship — these are starting points, not scripts.

Email vs Invoice Portals vs Post

Email with a PDF attachment is the standard for most small-business and freelance invoicing. It works, clients expect it, and there is a clear paper trail.

Some larger companies require you to submit invoices through a portal — Ariba, Coupa, Tipalti, or a custom system. If a client tells you to use their portal, use it. Emailing the invoice instead will likely mean it never enters their AP system at all. Ask during onboarding: "How should I submit invoices?"

Postal mail is rarely needed now, but a handful of government contracts and traditional industries still require a physical copy. If so, send the paper invoice and a PDF by email as backup. Mark both with the same invoice number.

Timing: When to Send

Same day you deliver. Every day between finishing work and sending the invoice is a day added to your payment timeline that you control entirely. Deliver on Thursday, invoice on Thursday.

Time of day matters less than you might think, but mid-morning on a weekday (Tuesday through Thursday) puts you at the top of the inbox when AP teams are processing. Avoid Friday afternoons and weekends — invoices sent then tend to get buried under Monday's email pile.

For retainer clients, pick a consistent date each month. The 1st or the last working day of the month are both common. Consistency makes your invoice expected rather than surprising, and expected invoices get processed faster.

For more on reducing payment delays, see our guide to getting invoices paid faster.

Following Up When There's No Response

You sent the invoice. The due date passed. Nothing. Here is a follow-up sequence that works without burning the relationship:

Day 1 past due: short, friendly email. "Hi [Name], just checking in — Invoice #047 was due yesterday. Let me know if you need anything from my end." Assume it was an oversight.

Day 7: slightly more direct. Reattach the PDF. "Following up on Invoice #047 (£3,200, originally due 15 July). Could you confirm this is in the payment queue?"

Day 14: escalate to your main contact if you've been emailing AP. A brief phone call or direct message often resolves things faster than another email.

Day 30+: formal overdue notice. Reference your contract's late-payment clause. At this point, the tone shifts from reminder to demand.

Our invoice writing guide covers late-fee clauses and what to include on the invoice itself to support your follow-up position.

Common Sending Mistakes

Create properly formatted invoices with our free invoice generator.