This document discusses HMRC self-assessment tax returns in the UK. It explains that around one in three taxpayers are sent a self-assessment tax return automatically each year if they meet certain criteria like being self-employed, having multiple income sources, or owning property. It outlines the three documents sent with a paper tax return: the return form, a guide to filling it out, and a tax calculation guide. Taxpayers are responsible for submitting a return if required even if they don't receive one. The document also provides contact information for HMRC for additional support or alternative formats.