Maybe we should be safe here, but the id3 v2.3.0 and v2.4.0 specs are very explicit about this:

v2.3.0:
> All Unicode strings [UNICODE] use 16-bit unicode 2.0 (ISO/IEC 10646-1:1993, UCS-2). Unicode strings must begin with the Unicode BOM ($FF FE or $FE FF) to identify the byte order.


v2.4.0:
> $01 UTF-16 [UTF-16] encoded Unicode [UNICODE] with BOM. All strings in the same frame SHALL have the same byteorder. Terminated with $00 00.