Tier 3: Low skilled workers
The third tier of the new points based UK visa service is designed to cater for people immigrating to the UK in order to perform temporary low skilled work. The new tiers immigration service will replace existing structures such as the Seasonal Agricultural Workers Scheme (SAWS) and the Sectors Based Scheme (SBS) and will grant leave to enter the UK to migrants from countries with which an effective returns arrangement with the United Kingdom is in place.
Entry requirements
Just like the current UK work permit visa 
structure, a tier 3 visa application is primarily an employer led process. Like work permits, companies looking to sponsor workers under the tier 3 visa system will need to attempt to source labour domestically before recruiting from outside the EU. Tier 3 visas are intended to cater for the fluctuating need for low skilled workers throughout the year and will be used in circumstances where the Skills Advisory Body (SAB) identifies a shortage area which cannot be filled by the domestic workforce.
As with tier 2 visas, tier 4 visas and tier 5 visas, entry to the UK under a tier 3 visa will require a certificate of sponsorship as part of the application. For tier 3 visas the sponsor will be the operator of a particular low skilled worker scheme and the certificate will serve as confirmation that the applicants who are immigrating to the UK will be bound by the terms of the route.
Unlike a Tier 1 visa or a Tier 2 visa, applications at the tier 3 level do not constitute a route to settlement and will not provide you with an an opportunity to apply for permanent residence in the UK. A visa for the third tier of the five tier immigration system will be granted for a maximum of 12 months and you will be obliged to return home at the end of this period. Switching to other tiers is not permitted and UK visas of this kind do not make provision for spouse and dependant immigration. This means that although the marriage visa , fiance visa and unmarried partner visa will continue to function independently of the new five tier system system, they will not be relevant to applications of this kind.