Among the four branches of the U.S. military – Air Force, Army, Marines and Navy – only the Navy has a rank known as lieutenant commander. This rank is the fourth step up the scale of commissioned officers, or O-4, and equivalent to major in the other three branches.

Basic Pay

A U.S. military officer's basic pay is determined by the yearly National Defense Authorization Act. It can be found by cross-referencing the officer's rank, in this case O-4, by the number of years he has been in the service, anywhere from less than two on up to more than 38. For instance, on the 2013 pay chart, a lieutenant commander with less than two years of service would earn the minimum $4,362 a month – $52,344 a year – while one with more than 18 years of service would earn the maximum $7,284 a month – $87,408 a year.

Basic Allowances

Members of the military who live off base also receive a Basic Allowance for Housing. This allowance varies based on rank, whether or not the service member has dependents and where she is stationed. A lieutenant commander would again use the O-4 line, then look up her particular duty station on the appropriate chart, "with dependents" or "without dependents." Allowances for a lieutenant commander range from just over $1,000 to more than $4,000 each month on the 2013 charts. In addition, a lieutenant commander will receive the Basic Allowance for Subsistence that all officers receive, which was $242.60 a month as of 2013.

Cost-of-Living Allowance

Lieutenant commanders, like other service members, can also receive a Cost-of-Living Allowance from the Navy if they are stationed in certain high-cost areas of the United States or their primary dependents live in one of those areas while the service member is on overseas duty. In addition to duty station, rank and time in service are factors in determining this allowance. A lieutenant commander's "COLA" may range from less than $30 to more than $400, depending on seniority and station.

Special Pay

Lieutenant commanders may also be eligible for special pay, depending on their military specialty and other factors. For instance, Naval aviators are eligible for additional "flight pay" starting at $125 a month – dependent on length of aviation service. Likewise, those serving in combat situations may receive hostile fire and imminent danger pay of $225 per month, or those with valuable skills such as foreign languages may receive a bonus for their proficiency. In some special pay cases, rank is a factor, while in others, the pay is the same for all sailors or officers.