MyTaxDigital is a surprising gem, and its free.
MyTaxDigital's home page is a bit off-putting but don't let that discourage you and it requires a bit of exploring and trying things out to understand how things work, but it is the most intuitive interface I have come across. Its completely free and I discovered that this MTD website gives you the option, if you prefer, to enter your figures just as you would on HMRC’s own self assessment form, in simple data entry fashion, nothing fancy. It also uses the similar language used on the original form to minimise confusion so if you don’t like the extra fancy bells and whistles the other MTD websites thinks is clever but is actually confusing, MyTaxDigital will be perfect for you.
Another advantage of MyTaxDigital is that it was the only one that I came across (I also tested ClearBooks, QuickFile and TaxHeaven) that has entry boxes for HMRC’s Box 37 and Box 45 (named “Rent a Room exempt amount" and"Unused residential property finance costs brought forward" respectively on the original HMRC self assessment form) that are available to enter figures immediately. For the other MTD websites, when I contacted their customer services, they told me those boxes do not currently exist but will appear on their respective websites in the final quarter, just before you are due to submit the whole final return for the full year which is fair enough I guess because these specific figures relate to the whole year anyway, not a quarter. However I didn’t want to take the risk of waiting to find out if what they said was true, so I am sticking with MyTaxDigital because all the boxes are available to see and enter from Day 1 and for the simple data entry interface it provides.
The home page of MyTaxDigital is off-putting because of the obvious use of AI in producing their videos but at least they provide helpful videos! And when you ask for help from their AI bot on navigating their website, the bot is surprisingly knowledgeable. If the businesslike MyTaxDigital interface doesn’t take your fancy, I would suggest the more attractive looking mtd website called TaxHeaven, my strong second choice because their support is great (2 days response time max by owner himself), unlike ClearBooks or QuickFile who are reluctant to help free users and I suspect will eventually remove their free tier entirely.