Visa numbers are always allotted for all documentarily qualified applicants with a priority date before the relevant cut-off date, as long as the case had been reported to VO in time to be included in the monthly calculation of visa availability. There is no exception to this principle. Allocations outside the regular monthly cycle are possible only in emergency or exceptional cases, and only at the request of the office processing the case. The rate of return of unused numbers may fluctuate from month to month, just as demand may fluctuate. Lower returns mean fewer numbers available for subsequent reallocation.
Fluctuations can cause cut-off date movement to slow, stop, or even retrogress.
Retrogression is particularly possible near the end of the fiscal year as visa issuance approaches the annual limitations. The annual per-country limitation is a cap which visa issuances to any single country may not exceed. Applicants compete for visas primarily on a worldwide basis. The country limitation serves to avoid monopolization of virtually all the annual limitation by applicants from only a few countries. This limitation is not a quota to which any particular country is entitled, however.