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What’s the Best Subject Line for Sending an Invoice? (5 Options)

Table of ContentsUpdated Oct 11, 2019

Email subjects for invoices aren’t all that different from subject lines in any other scenario.

There’s just one hang-up: Sending an invoice can be a little awkward. 

Which means lots of people have a hard time knowing what to say when sending an invoice via email.

Below, you’ll find 6 perfectly acceptable email subject line options for the next time you need to send an invoice.

And if you’d rather not worry about it, just use an invoicing app which will handle all your communication for you. The one we recommend the most is FreshBooks because they follow-up with clients who “forget” to pay

Here are our top 6 email subject line recommendations when sending an invoice:

email subject for invoice laptop gmail subject line

1. “Invoice ####”

The first and most basic email subject for invoicing is to just write Invoice #### where the ####s are, of course, the number of the invoice you’re sending. It would look something like this:

Example subject line: Invoice #1234

This email subject line works when sending invoices because it’s basic, simple, and to-the-point. Of course, it’s also a bit cold. 

We recommend using this email subject for invoicing an accounts payable department or some other faceless organization.

If you’re sending an invoice via email to someone you’re building a relationship with, like a client, try a warmer email subject line for invoicing them instead (more below).

2. “Invoice #### Due. Thank you!”

To warm it up a bit, you can make your email subject line a bit more conversation (and grateful) by adding a simple “thank you” to your email subject line when sending an invoice.

Example subject line: Invoice #1234 Due. Thanks a bunch!

This keeps it very straightforward and clear, but also let’s your client know you’re grateful for both their business and a prompt payment of your invoice.

3. “Here’s your invoice (####)”

To warm up even more, make your email subject line for invoices more conversational. If you were delivering your invoice in person instead of emailing an invoice, you’d never hand a piece of paper to someone and say “Invoice #1234.”

Instead, you’d probably say something like “Here’s that invoice we discussed.” Which is exactly what’s happening in this email subject line for invoices.

Example subject line: Hey! Here’s the invoice we talked about (#1234)

4. “Sending invoice as requested (####)”

If you’re not exactly friendly (or casual) with the person you’re sending the invoice to, you may want to just consider remind them, in your email subject, that you had previously discussed the invoice you’re sending them.

Example subject: Sending Invoice #1234 as requested

This can also help lessen the awkward “where did this invoice come from?” moment some clients experience when they’re dealing with lots of different contractors.

5. “New invoice from [company name]”

Another way to help your clients stay organized and remind them who’s sending the invoice via email is to include your company name (or your personal name if you’re a freelancer operating under your own name).

Example email subject: New invoice from Jean Yves Design Co.

Or any combination of the above choices…

Of course, you can combine any of the above ideas to form the ideal email subject line for sending invoices. 

Figuring out what to say when sending an invoice via email is a matter of finding your own style, experimenting, and adjusting as needed.

What about past-due or overdue invoices?

If you have a collection of past-due or overdue invoices, try using one of our 3 free past-due invoice emails in order to get paid what you’re owed asap.

Bonus resources for better invoicing:

If you’re going to be sending more than one invoice to your clients, we suggest not necessarily always sending manually via email. Sometimes asking for payment can come off as rude if not handled perfectly which is an added stress you don’t need. 

Instead, try one of these invoicing tools we highly recommend:

FreshBooks (try free 30 days)

We’ve been working with freelancers (and freelancing ourselves) for over a decade. And, by far, the most popular invoicing tool we hear about from our community is FreshBooks.

With FreshBooks, you can generate invoices in 30 seconds or less and automate follow-up emails to remind your clients their invoice is due. All via email without manual work from you.

Andco (try free with one client)

Another great option for sending invoices to your clients and managing all of the other aspects of your freelance business is With, you can send freelance proposals, generate invoices, get paid quickly and manage your time and tasks.

Honeybook (try free 30 days)

Another great option for sending invoices to your clients (and managing whether your invoices get paid) is Honeybook. It’s also got some great bookkeeping, reporting, time-tracking, and project management options. 

Bonsai (try free for 14 days)

Finally, we highly recommend one last invoicing tool for freelancers called Bonsai. Built by freelancers, for freelancers Bonsai is an all-in-one business suite for managing every aspect of your freelance business.

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Written by Preston Lee

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Preston Lee is the founder of Millo where he and his team have been helping freelancers thrive for over a decade. His advice has been featured by Entrepreneur, Inc, Forbes, Adobe, and many more.

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  1. Michael Wormald says:

    Juan, 60 day late payment will cause lot of problems for me. I use SlickPie cloud accounting to send automated payment reminders for my small VOIP business for those we don’t have credit card on file and most of my clients pay within 14-20 days.

  2. Just out of curiosity sake:
    I run a small design studio in Spain and is a common thing (and I know it is not just me but a issue affecting the whole designer’s community around here) not only having to wait more than 60 days to get paid; and sure there are individuals and companies that respect agreed payment terms but usually –and sadly– those are the least.

    To add on this, the project managers (mine e.g.) or studio accountants or whatever any other person that is in charge of the monetary thing in the studios, hace to waste countless hours chasing the payments. Payments that were known & agreed upon the quotation, contract and/or any other form of deal.

    And I don’t want to mention the ocassions when the client bargains on the invoice which is 99% of the times an exact mirror of the quotation…

    That leaves only the big (really big) studios or agencies get paid as expected and in due time.
    We are suppossed to have regulatory laws that prosecute late- or no-payers-at-all but it usually involves a visit to the attorney or legal consuelor (that also costs you money).

    My question is, are we the only place like this? Because as far as I can read in forums like this one or when I talk to other overseas colleagues, paying beyond 3-4 weeks is not only radically unsusal but also unprofessional.
    What is the medium payment time over there?

    Sorry for the long thread but is a question that is always burning in mi mind…

  3. Do you guys have any recommendations for collection agencies for when a client doesn’t pay their contractually bound invoice? Been trying to find a collection agency for small businesses but am not having much luck.

    1. I’ve only had to use a collection agency once. I was able to find one in my local community. Are you in a small town, or a mid-size to large city? Depending on where you live, you should be able to find one where you are.

  4. Very simple and efficient great! thanks

  5. Hi Brad,
    thanks for these tips.
    What I usually do after completing my task I call my client to inform him that I have finished my work and that I will issue an invoice with due date – 14 days (or any other we agreed on).
    I use Invoicing software to issue invoices, they have auto-reminders so I don’t have to send the reminders myself and I am quite lucky because in most cases I get paid on time.

    One more tip – it’s good to double check that we are sending invoices to the right person our clients company.

  6. Brittany Klein says:

    Thanks this was helpful! Not sure if this is good to do or not, but I usually offer some kind of a discount to repeat clients, so I’m always sure to show lines for discounts and for items I haven’t charged for. My initial meeting with the client is free, and I include that on the invoice with amount charged $0.00,

    Unfortunately, I’m on the “send a lot of reminders” portion for one client. Do you include the ramifications for late payment on your invoice? Such as late fees after 21 days?

    1. Hi Brittany, I always include a note about late fees in all my invoices so clients know from the start that being late could cost them more money:

      “Payment due within 30 days of invoice date. Invoices more than 60 past due will incur a $25 late fee.”

      I’ve only had to apply the late fee a couple times. Most clients pay within the initial 30 day period.