This month HMRC starts signing people up to an obligation without choosing the tool that meets it. The choosing was always the hard part

There is a particular kind of help that makes things worse, and it has a shape. It removes the easy step and leaves the hard one.

From this month, HMRC begins signing up sole traders and landlords who should already be inside Making Tax Digital for income tax and have not registered themselves. It will happen in stages over the coming months. On the face of it this is a courtesy. The department has noticed you are late and is doing the paperwork for you.

But registration was never the difficult part. Automatic sign-up does not organise anyone's bookkeeping, does not submit anything, and above all does not choose the software. It confers the duty. The decision that actually costs time and money and attention stays exactly where it was, and it now has to be made by someone who has just been told they are behind.

Consider what that decision looks like. HMRC publishes a list of recognised products, and the list is long. When the Public Accounts Committee looked at the equivalent list for VAT it counted more than 500 products and recorded, drily, that many customers said they felt overwhelmed when having to choose from it. The Committee also heard that some products advertised as costing nothing did not, and that others carried features nobody had explained.

Now add the word free to that list, because it is on it. Several genuinely good products cost nothing to start. That is not a trick, but it is a design. A no-cost tier is the cheapest way ever invented to acquire a customer who did not want to be acquired, and it works best precisely on people choosing quickly, under obligation, with no basis for comparison and no appetite to build one. The conditions attached to those tiers are real and they are knowable, but knowing them takes the sort of afternoon that a person who has just had a letter from HMRC does not have.

There is a version of this that goes well. Defaults are powerful and mostly benign. Automatic enrolment in workplace pensions worked because the default was the whole decision: you were in, contributions went out, and the hard choice was made for you by someone with an interest in getting it right. Here the default covers the announcement and stops at the threshold of the thing that costs money.

None of which is an argument that people cannot manage it. Most have. More than 436,000 of the 570,000 who signed up filed their first quarterly update on time last month, and HMRC's own research on the VAT phase found that most people found the software easy once they were using it. The pattern in that research is worth holding onto: people dread it beforehand and rate it more kindly afterwards.

The question is not whether the average person copes. It is what the design does to the people at the edges, who are late because they were struggling, and who are now being enrolled fastest into the decision they were least equipped to make.