Frequency allocations are generally managed through legislation and regulation by individual governments. Internationally, there are differences in frequencies allocated for RFID applications although standardisation through ISO and similar organisations is assisting in compatibility.
For example, Europe uses 868 MHz for UHF and the US uses 915 MHz. Currently very few frequencies are consistently available on a global basis for RFID applications. Three frequency ranges are generally used for RFID applications.

In general, low-frequency passive tags have an effective range of approximately 30 cm, high-frequency passive tags around 1 m and UHF passivetags from 3 to 5 m. Where greater range is needed, such as in container tracking and railway applications, active tags can boost the signal to a range of 100 m.

In the EPC website you can find a report that provides an overview of the Ultra High Frequency (UHF) regulations worldwide. It is regularly updated and includes a status indicator, the frequency band authorized in the country, the power level, the communication technique, a brief comment and the contact details of the national body responsible for regulations.
In Europe there are four major responsible organisations for radio regulation, which work together on several stages. These four organisations are:

• The International Telecommunication Union (ITU) where governments and members of the private sector meet to discuss and coordinate global telecom networks and services. Its members are en- gaged in different fields of standardisation: policy-making and regulation of tele- communication, network operators, equipment manufacturers, hardware and soft- ware developers, organisations for regional standards and financing institutions. ITU’s activities, policies and strategic direction are determined and shaped by the industry it serves.
• The European Conference of Postal and Telecommunications (CEPT) with 47 administrations members. Within the CEPT, the Electronic Communications Committee (ECC) operates with several management groups. The major ones are Frequency Management (FM), Spectrum Engineering (SE) and Regulatory Affairs (RA). The group Frequency Management deals with regulations and frequency decisions while the group Spectrum Engineering defines compatibility and sharing between different services and the SRDs.
• The European Telecommunications Standards Institute (ETSI) is a radio standardisation organisation for short range devices (SRD). IN ETSI ERM deals with SRD standards and standards for other radio systems. There are some 40 Task Groups (TG) under ETSI. ETSI is the most important TGs concerning radio regulation TG28, TG34 and TG 31A, TG31B and TG31C. These are designed for Short Range Devices, including RFID and the Ultra Wide Band (UWB). Deliverables from ETSI are so-called ETSI standards and technical reports or System Reference Docs (SRDocs).
• Moreover, the EU plays a very decisive role in the field of radio regulations. The EUaddresses EU policies regarding telecommunication field frequency and issues EC directives. These policies are worked out by the RSPC (Radio Spectrum Policy group). RSCOM (Radio Spectrum Committee) implements these policies in coordination with the CEPT/ECC.