Thanks for the responses.
Well, yes I did get a Staging Date from the Pension Regulator when they first wrote to me, and I can still find this against my PAYE reference number using the online tool.
However, as a company, we meet the criteria for not being an employer for the purposes of automatic enrolment, and the Regulator has confirmed that, under the Pensions Act 2008, automatic enrolment duties "no longer apply to us".
The help text against the Staging Date entry field says "the date the new laws will apply to you as an employer for the first time" so I am not comfortable entering any date here unless there is also a box to tick saying that the new rules don't apply to us ... I don't won't ClearBooks to start hassling me to do other stuff after this date.
We are aware that we have to inform the Pension Regulator If our company's employer status changes, but that is unlikely to happen before the initial staging date given, if ever, and I don't see that ClearBooks needs to concern itself with that until it actually happens.
I leave it blank for now.