If you have clients who want to bring in foreign workers on H-1B visas, they better act quickly.

Petitions for H-1B visas subject to the fiscal year (FY) 2015 cap will start being accepted on April 1 by the U.S. Citizenship and Immigration Service (USCIS). H-1B visas allow employers to hire foreign workers with specialized knowledge or technical expertise, such as scientists, engineers, or computer professions. Each year, only a limited number of these visas are issued. Again this year, the cap for those with bachelor’s degrees is 65,000, and another 20,000 will be issued for workers with master’s or higher degrees obtained at universities in the United States.

Experts expect the caps to be met within the first week of the filing season. Immigration attorney Marc Klein told CNBC that at least 160,000 applications are expected.  That would top both 2012′s petitions (134,000) and 2013's (124,000). A computer-generated selection process, or lottery, will be used to determine which petitioners will get the available visas.

A big driver of this demand is the need for foreign workers who can fill contract Information Technology (IT) positions. Hiring has been very hot in the IT sector. Due to the nature of the work, many of the open positions are being filled on a contract basis. That is increasing the competition for highly skilled technology contractors and forcing companies to look overseas for them. Companies are also submitting H-1B applications for accounting, advertising, and architecture positions, Klein said.

The technology community has been urging Congress to increase the cap, but the larger debate on immigration reform in general has prevented any changes. In the meantime, companies will have to make do with the limited number of H-1B Visas currently available for FY 2015.