"It is important to remember that the establishment of a monthly cut-off or "Current" status for a numerically controlled category (preference or Diversity) applies to those applicants who were reported prior to the allocation of visa numbers for that month. For example, all qualified applicants who were reported to the Visa Office in time to be included in the calculation of the September cut-offs, who had a priority date or rank-order number before the relevant September cut-off, would have been allotted visa numbers for September. There would be no expectation, however, that sufficient numbers would be available for the processing of cases which subsequently became eligible for final action during that month. Additional numbers may be allocated outside the regular monthly cycle, but only to the extent that such numbers remain available under the applicable annual limit. The availability of additional numbers is subject to change at any time and should never be taken for granted. This is especially true late in the fiscal year when numerical allocations are often close to or at the annual limits.
When applicants fail to appear or overcome a refusal (even for reasons beyond their control) during the original month of scheduled interview, they risk not having their case processed later in the fiscal year. This is because the unused numbers that had originally been allocated for their case are returned at the end of their interview month to the "pool" of numbers available for allocation in subsequent months to other applicants being reported for their "first time" interview.
EMPLOYMENT-based Third Preference:
China: Rapid forward movement of the cut-off date, as a result of there being insufficient demand to use all available numbers, allowed the category to reach the Worldwide Third preference cut-off date in May 2013. The continued lack of demand has allowed the "otherwise unused" numbers available under that limit to be provided for use in the China Employment Third preference Other Workers category. The continued addition of those numbers has allowed the cut-off date for that category to reach the China Third preference date for November. This is the same action which has been possible for the Other Worker category in other "oversubscribed" countries such as India and Mexico. A sudden increase in demand for China Employment Third preference visas could require corrective action in the China Other Worker cut-off date at any time." - CA/VO: October 9, 2013.