The expression "USD salary" is a shorthand expression which means a salary amount is given in United States dollars. Job seekers often read job postings that include "USD salary" information for the position. When you complete an application, you may also have to submit "USD salary information" within your employment history.
Job Posting Purposes
The primary motive for stating a potential salary in U.S. dollars on a job posting is to ensure that international candidates recognize the meaning of the amount given. Confusion can arise if you only say "dollars" or use a dollar sign; some other countries, including Canada, also call their currency "dollar," and its value is not the same as a U.S. dollar. For postings that attract international candidates, you allow applicants to convert the potential salary into their own currency and compare it to similar jobs at home and abroad. A May 2011 Business Insider article noted the substantial difference in take home pay in Moscow relative to New York, so having the USD amount is helpful.
A similar benefit is gained on an application. You avoid misunderstandings when an international candidate submits an amount, such as "50,000," without a specific denomination. By asking for salary history and expectations in U.S. dollars, you ensure you get the details you want.