Install the WP-Invoice plugin to send invoices from WordPress

Learn how to add invoicing capabilities to your WordPress site by using the WP-Invoice plugin.

WordPress is one of the most widely used blogging platforms. However, it's not limited to blogging. In fact, WordPress has become so flexible that it's a capable foundation for many types of sites. Thanks to its powerful plugins, you can bend and shape a WordPress installation to do just about anything. One thing you may want your WordPress site to take on is invoicing.

Anyone running his or her own business (especially a consulting business) knows that invoicing is crucial to success. Without an efficient, reliable means to invoice clients, getting paid can quickly become a problem. A handy WordPress plugin specifically created for the task of invoicing is WP-Invoice.


With WP-Invoice, you can:

  • Create invoices from the WordPress control panel;
  • Prefill customer information from the WordPress user list;
  • Send invoice notifications with a secured link to the web-invoice;
  • Accept credit card payment via Authorize.Net or MerchantPlus NaviGate;
  • Use PayPal;
  • Set up recurring billing (using's Automated Recurring Billing);
  • Force web-invoice pages to SSL mode;
  • Archive old invoices;
  • Use completed invoices as templates;
  • Customize tax label, states input, and PayPal button URL;
  • Create users directly from WP-Invoice;
  • Customize billing settings on a per invoice basis;
  • Customize invoice notification email on a per invoice basis; and
  • Use templates for invoice notifications, reminders, and receipt.

Installing WP-Invoice

There are a couple of ways to install this plugin, though I've decided to approach this in the easiest possible way -- through the WordPress dashboard. Follow these steps:

  1. Log in to your WordPress Admin tool (usually this is done by adding /wp-admin to the end of your WordPress URL).
  2. Click the Plugins section.
  3. Near the top of this page, click Add New (Figure A).
  4. In the search field of the new page, enter wp-invoice and click Search Plugins.
  5. Click Install Now for the WP-Invoice entry (not wpinvoice).
  6. When prompted, click OK.

Figure A

WordPress makes it easy to install plugins. (Click the image to enlarge.)

After the plugin installs, you'll be asked to activate the plugin, which you should do. Then, you'll be directed back to the plugins page of your WordPress dashboard. You're ready to start setting up your invoicing tool.

Setting up WP-Invoice

Warning about Apache mod_security

In some instances, Apache mod_security blocks the saving of settings for WP-Invoice. To get around this, you'll need to temporarily disable mod_security, configure your WP-Invoice setup, and then re-enable mod_security. The easiest way to temporarily disable mod_security is to create an .htaccess file in the document root of the web server with the following contents:

SecFilterEngine Off
SecFilterScanPOST Off

Save that file and restart Apache. After you take care of the final setup of WP-Invoice, make sure to delete or rename that .htaccess file and restart Apache. If you don't remove that file and restart the server, Apache will be wide open and insecure. The developers of WP-Invoice are aware of this issue, but they haven't found a fix yet. Remember: don't forget to turn mod_security back on.

Setup instructions

Click the new Invoice entry in the left-hand navigation to reveal the WP-Invoice first use setup options (Figure B).

Figure B

When you first use WP-invoice, you'll be presented with this page. (Click the image to enlarge.)

Go through the options and set them to meet your needs. To set up your payment method, select it from the Default Payment Method drop-down. If you select PayPal (as I have), a new section will appear at the bottom of the page (Figure C), which is where you'll need to configure your payment information.

Figure C

Setting up PayPal as your default means of payment. (Click the image to enlarge.)

After you set the default payment option, you'll gain access to the rest of the plugin settings. Go to the Main tab to add company information and to enable the plugin to use custom templates. To do this, you must check the box for Use Custom Templates and then click the Install button (Figure D).

Figure D

Enabling WP-Invoice to use custom templates. (Click the image to enlarge.)

When you click Install, you must click OK in the warning box -- the warning states it will overwrite any theme files you currently have in your wpi folder. You'll want to go through every tab in the plugin to make sure it is configured to meet your needs.

But before you start using the system, you need to create line items to use in the invoices. To do this, follow these steps:

  1. Click the Line Items tab.
  2. Click Add Line Item (Figure E).
  3. Enter the information for the line item.
  4. Add as many line items as necessary.
  5. Click Save.

Figure E


Add Line Item (Click the image to enlarge.)

After you go through all of the plugin's settings, you're ready to start using the tool.

Using WP-Invoice

Go to Invoice | Add New and then enter the necessary information. After you save the invoice, go to View All and then you can send the invoice by opening it and clicking Send Notification (Figure F).

Figure F

Sending invoices and notifications is simple. (Click the image to enlarge.)

After you send an invoice, if you don't hear back from the client in an appropriate time, you can send an invoice reminder from this same location -- just select a different template.

From that point on, the system is incredibly user-friendly and ready to help you keep your invoicing as reliable and ready to serve as possible.

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