About a million taxpayers can participate at the moment in the live system. The question we don't know the answer to is when it will become mandatory.
I don't think HMRC will set a date until there is some certainty as to what is happening with Brexit.
I don't have any inside knowledge on this, but I would think that if they were to make it mandatory they would have to indicate this before the start of the tax year. Although as it is currently designed you don't have to submit the data until the usual 31/1 deadline (the plan is to be more timely than that) I think it is a bit late for now to start it for 2020/21. However, it would be possible.
I would expect them to make it mandatory for a small number of taxpayers first, possibly those with higher taxable income.
MTD suppliers have to pass a test to get production credentials so that live submissions can be made. I passed that test on Wednesday and should have production credentials soon.
The list of suppliers (see below link) is a lot shorter than VAT because there is a lot more work in doing it. There are, however, brexit induced delays on getting onto the lists so I would not expect to appear on the lists for a month or so even though I probably could do live submissions next week.
As Joanne knows I have a test interface that people can use. If you want to play with ITSA (when you have some spare time) you are welcome to use that.
I am talking to HMRC about the period end dates. It would be a bit silly to have to have different quarters for VAT and ITSA.
