You can upload up to 10 documents at a time; split larger sets into batches.
Besides PDF and JPEG, HMRC accepts XLSX, ODS, DOCX, ODT, PPTX and ODP.
How to do it with Requisito Listo
Open «HMRC: send documents for a check».
Scan the pages with the camera or pick a PDF or photos you already have.
Put the pages in order.
The app builds the PDF under the size the portal asks for.
At the end you'll see a checklist: size, file weight, background and format. If something doesn't comply, it tells you what to fix before the portal rejects it.