Pay Grade

• Like all branches of the military, army officer salaries differ based on pay grade or rank. For example, a first lieutenant (O-2) with three to four years of service earns a monthly base pay of $4,149 per month, while a captain (O-3) with the same amount of time in the service earns $4,479 per month, according to the Defense Finance and Accounting Service.
  
  

Years of Service

• Officer base pay is also affected by number of years of service. For example, the second lieutenant (O-1) with two or fewer years of service earns a base monthly salary of $2,745. On the other hand, a second lieutenant with between eight and 10 years of service earns a base monthly pay of $3,454.
  
  

Allowances

• Army officers, and all military personnel in general, earn a large part of their salaries in benefits and allowances. For example, one key component of an officer's salary comes from the basic housing allowance, or BAH. These allowances depend on the officer's pay grade, location and whether she has dependents. An O-3 stationed in Oakland, California, earns $2,346 per month in housing allowances, while an O-4 in San Bernardino, California, gets a monthly housing allowance of $1,554.
  
  

Bonuses

• In addition to base salary and allowances, U.S. Army officers can earn extra income if they qualify for different bonuses. Army special warfare officers are eligible to earn a bonus of $15,000 if they meet special warfare eligibility requirements and agree to remain on active duty for at least one year. Also, officers serving in a combat environment can receive "Hostile Fire and Imminent Danger Pay" of up to $250 per month for each month in which the officer was on duty and exposed to, or in danger of being exposed to, imminent or dangerous fire.