Google Inc. announced Tuesday it offering a referral fee worth $15 for every new Google Apps for Business user. This promotion is to increase the applications' number of users.

Google Apps for Business is a service that allows users to share files. It is Google-in-one package that integrates Gmail, Google Calendar, Docs, Drives, Groups, News, Play, Sites, Talk, and Wallet. It offers a 30-day free trial then charges the account $5 per month or $50 for a year. A single account can have at least 50 users. However, the app has been criticized due to its lack of administration, customization, and low return-of-investment (ROI) for businesses that availed the service. As of July 2012, the service is reportedly being used by 6,000 businesses which are quite low considering that it is operational since 2009.

There comes marketing. To attract more customers, the software giant is giving its existing users $15 for every new user they referred for the service. However, the program is only applicable to users in the United States and Canada, ZDNet reported.

"Joining is simple," said Google Apps Marketing head Prajesh Parekh in a blog post. A user just needs to register and provide his name, e-mail address, a valid taxpayer ID, and the bank account details where he wants to receive the payment. After registering for the program, he will get a unique referral link. Every time a new user signs up for Google Apps for Business through his referral link, he'll get paid. A user can refer an unlimited number of users.

The referral program's fine print, on the other hand, will reward the user for each referral customer's first 100 users. A user is defined as an individual account that belongs to the customer domain. The referral amount will be based on the number o users who will pay for 120 days, at the least.