Extra Time for Returning PIP Review Application

Hi,

My wife received her review application on 8th October 2021 and they want it returned by 30th October. They have said in the letter that we can request an extension but we're not sure what the maximum extension they can give. My wife has considerable processing difficulties and it takes a long time to gather information and formulate it. Even if we had help it would still require my wife to have to still gather the information, formulate it to pass on to an advocate. We want to ring up and be able to clearly express the need for an extension of at least 6 weeks because even the energy to do this will mean sacrificing daily tasks, self-care, important physio and this is even if they give 6 week extension. Ideally we could do with more weeks than this as there is just so much evidence and work to do on the application. What rights does my wife have on this as somebody with valid hidden disabilities (autism condition, audio processing disorder, spatial auditory processing disorder, dyslexia, dyspraxia, adhd and other neurological processing difficulties). We do not want them to be pulling the wool over our eyes and would like the correct wording of what to ask so that we are not being taken advantage of when struggling on the phone trying to ask. Thank you in advance