Two warnings: Despite HMRC's own recorded message stating that HMRC accepts the new government (gov.uk) generated access codes to prove you have power of attorney to act in tax measures for someone else, you'll find that very few call handlers know about it or how to operate it. Then having spent over an hour coaching one of them through it and them confirming that they could see that I was approved to act for my father, I was then told that I couldn't actually do anything and would need to send in the original power of attorney document by registered delivery. There seems very little point HMRC claiming they accept the code system unless someone from HMRC can tell me any differently. I would also urge extreme caution parting with the original POA document as once I'd sent mine in as instructed, HMRC then don't issue a signature to Royal Mail as any form of proof of receipt! On multiple calls to confirm the arrival and track the document I was given differing and increasingly longer lengths of time for them to have processed it, the latter of which being 3 weeks! after receipt. At no stage was any of this process explained to me or was there any regard for the exceptionally valuable nature of this original document which is needed back in a timely manner to act as proof to other agencies in complex life matters. All call handlers seem very unclear on anything to do with any of this and can't refer me to any written procedures or reassurances governing this process.