The Government has a code of practice on consultation which sets out how central Government's formal, written consultation exercises should be run. The first criterion of the code states that such consultation exercises should last for a minimum of 12 weeks. The code acknowledges that there will sometimes be circumstances that require a consultation period of less than 12 weeks but states that this should be the exception and should be avoided wherever possible.
No guidance exists on maximum periods for written consultations.
Public bodies outside of central Government are free to adopt their own approaches to consultation.