Writing an Invoice: Rules Not To Follow

Accounting your invoices can be stressful and confusing, especially when you deal with many customers each day. Some of the worst invoicing errors often come from a lack of focus on the accounting side.

However, these mistakes can also cost a lot of money and trust should they continue to escalate. What are some of the rules you should definitely avoid when it comes to writing an invoice for your clients and customers?

1. Bill the wrong person

It’s important to address the right person when writing an invoice for their company or legal business in general. You will most likely not bill the CEO themselves and often address the invoice to their accounting department or sales. The only time you should address a singular person is if you are doing business with a physical individual, not a legal entity.

However, since most of your work will involve companies and brands, writing an invoice to the wrong person is very easy. This is one of the most common issues that rear their head in invoices. It is easily solvable by resending the document and addressing it properly.

2. Send partial invoice documentation

Invoices are usually accompanied by other documents. These documents often include company policies, terms of use, as well as legality details. By not sending these documents to your client, you are effectively omitting information from them.

This partial documentation can often be overruled in the court of law because it appears as if you coerced your client. Send your entire legal documentation alongside the invoice in question. If nothing else, you will appear more professional and thoughtful in your client’s eyes.

3. The omission of important information

Speaking of important information, every invoice has a certain pattern to it. This means that it can be beneficial for you to create an outline that you won’t stray from. Some of the most important information that each invoice has to include is as follows:

  • The specific word “invoice” – this clarifies your intent towards your client and secures you legally.
  • The contract number, as well as detailed information on the services or products you provide for them.
  • Information about the payment you expect from your client and details about the deadline.
  • Clearly mark the amount of money requested from your client, as well as payment options.

Without these details, your client won’t be able to pay you properly. Worse yet, they will sometimes be able to take your product and legally seize it without having to pay you. Invoices are both your friend and enemy, depending on how much information you include in them.

4. Charge for wrong items

All it takes is to write the wrong name and address on the invoice for you to charge the wrong person. Large companies often sign invoices based on company names and known associates. Due to a large amount of paperwork involved, many invoices often glance over.

This means that it is fairly easy to charge the wrong company or a client for items they never received. The same can be said for sending more or fewer items to your client but stating an otherwise wrong number on the invoice.

Depending on the severity of your error, the client may or may not notice this error and act on it. Pay close attention to what invoice you are sending to whom. The same can be said of the number of items you list on each invoice.

Accountant writing an invoice


5. Poorly formatted invoice

Invoices tend to be read quickly and put aside. It is of utmost importance that these documents are formatted so that they are read as easily as possible. What this means is that you should follow a strict guideline based on your company’s standards when writing an invoice.

Clearly marking important sections such as client information, order details and pricing is very important. Should you have trouble formatting some of your invoices, you can check out Essay Supply and ask a professional writer to help you out.

However, formulating an internal invoice writing system should be done as soon as possible. Custom-made invoices can make sure that your company’s documents are clearly recognized as soon as they hit the inbox.

6. Be unprofessional

If you want to get rid of a client or tank your revenue sources, be as unprofessional as possible. Accounting departments that want to maintain their reputation should pay close attention to their wording.

The vocabulary you use when writing corporate documents speaks volumes about your brand and internal culture. Make sure to address your reader with respect, humility, and professionalism.

Punctuating an invoice with a phrase such as “With best regards” or “Best wishes” tells a lot about you. Go the extra mile and treat your clients with thankfulness. They could have easily gone to your competition but instead opted to use your services.

7. Unsigned invoices

Unsigned documents usually account for nothing once they land on your client’s table. Any document without an authorized signature is considered irrelevant, invalid and is returned to the sender.

While this is not a big mistake to make, it can delay your payment as well as order shipment. It can also make you look unprofessional and irresponsible, especially if it happens again and again. Make sure that your accounting department has all the invoices signed and sealed before sending them.

8. No invoice backups

Sending an invoice means that you are ready to ship the requested order. However, not saving the invoices that go to your clients is a big mistake. Not only will your accounting department have a hard time keeping tabs on everything, but you will also lose sight of incoming revenue.

It is very difficult to keep a steady workflow if you have no idea which invoice went to whom, when, and what their obligations are towards you. Make sure to create a backup of all the invoices that go out to clients and companies.

It is a good idea to store them on a cloud server, away from outside influences and malware. Losing your invoice library is considered one of the cardinal sins of accounting, so avoid it at all cost.

Send invoice email

9. Fail to market products

Use your invoice to market more products to your client. Sending an invoice without any marketing materials attached is a missed opportunity. You will rarely work with a company that requires a single delivery. Most companies tend to retain their partners for further work if they are satisfied with the cooperation.

Create a marketing brochure or a loyalty offer that you can send alongside invoices. Even if a small percentage of your clients answer to that material, your job as a salesperson will be successful.

10. Be old-fashioned when writing an invoice

You will hardly find a company that invoices exclusively through the email. Physical mail is becoming more and more archaic, even though transportation is fast and secure. Sending online invoices serves multiple benefits for both you and your client.

You can use invoice software in order to quickly and efficiently format documents before sending them. Best of all, once an invoice is sent via email, you will fasten the entire shipping and payment process. In doing so, you will streamline your workflow and ensure that your revenue doesn’t suffer.

Send a physical invoice via regular mail for safekeeping if you want to go the extra mile but focus on digital materials instead. It will show your clients that you are willing to embrace new trends and ensure that you are regarded as a professional company.


As you can see, it’s fairly easy to make a mistake while writing an invoice. Once you create a workflow for writing several invoices in succession, you will lower the possibility of making a mistake.

Take time to carefully read through contract information before sending invoices. A few extra minutes of attentive reading can save you a world of potential trouble.

James Scott
James Scott, an independent blogger, CEO at writing service Essay Supply and professional marketer Columbus, Ohio. He has more than 5 years of marketing experience and is passionate about professional and agile team management. Even the smallest member of the team can change everything, so a wise manager should do his best to deliver the best working experience for everyone. Connect me on LinkedIn!
James Scott

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