The API for MTD stuff is very open: https://developer.service.hmrc.gov.uk/api-documentation/docs/api https://developer.service.hmrc.gov.uk/api-documentation/do

The API for MTD stuff is very open: https://developer.service.hmrc.gov.uk/api-documentation/docs/api https://developer.service.hmrc.gov.uk/api-documentation/docs... And because of that there's tonnes of approved software, including loads of actually-free services: https://www.tax.service.gov.uk/making-tax-digital-software https://www.tax.service.gov.uk/making-tax-digital-software Including GNUCash, where you can register for your own developer key and file away for free - https://github.com/cybermaggedon/gnucash-uk-vat https://github.com/cybermaggedon/gnucash-uk-vat This seems like exactly the right way for a government to opt out of writing its own web front-ends.