HMRC is warning UK taxpayers to do their online self assessment tax returns by 31 January or face a £100 fine.

The deadline for paper-based returns has already passed and now there is a concern that people who send their returns online could be caught out by a lengthy registration process.

It can take up to seven working days for your online HMRC account to be confirmed and accessed after sign up.

As HMRC explained: “If you’re filing your return online for the first time, you’ll first need to register for online filing at You’ll be given a User ID, and an Activation Code will be posted to you within seven working days. Once you’ve received your Activation Code you can file online.”

Sounds like a rather inefficient online process, so it would be foolish to take any chances.