Designing an invoice may seem like a very simple task, but in reality, the design you choose can have serious psychological consequences. While your choice of color, layout, font, and other factors will not change the amount of money your customer has to pay their bills, but it can influence how they view your invoice within this context. Here are some things to consider when designing your invoices.
Color
Each color can convey a certain psychological meaning. Numerous studies have shown that red, for example, tends to be associated with negative numbers, urgency, and generally implies that action needs to be taken. Green and blue, on the other hand, tend to carry with them a sense of calm and relaxation. Over utilizing color can come off unprofessional though so we suggest using subtle clues instead. Consider making the amount owed red on invoices on past due accounts or utilizing blue and green in your layout on accounts that are paying on time.
Layout
It is important to frame how your customer views your invoice. Almost every business today outlines this idea of framing in order to increase the desired outcome. Clothing stores meticulously plan where items go in order to increase sales of high margin products. Groceries place items in certain places in order to draw customers up and down aisles. When it comes to invoices, we suggest placing important information near the top and with little else distracting from it. This makes the amount owed very obvious and keeps it fresh in your customer’s eyes.
Font
We have written on the importance of font choice in the past, but here are two important things 
to take into consideration. Just like color, any font you choose will convey a phycological meaning to your customer. It is also important to consider whitespace and font size when designing your invoice. Using bold font to emphasize a point can also help distinguish it from the words around it. While there is no perfect font, we do suggest going with something simple yet visually appealing. In many cases, less is more when it comes to font choices.
There is no such thing as the perfect invoice, but using scientific research to help guide your approach may be able to help your bottom line in the long run.