Nothing to do with your UTR, Dot, or "full" self-employment - you have to be self-employed for the Construction Industry Scheme to apply to you at all. You're talking about receiving gross payment under CIS instead of having money deducted by the contractor. One of the things you have to
show to get paid without deduction is that you earn over �30,000 a year, EXCLUDING money for materials. It's confusing, but that figure can be called either your net turnover or your gross profit. But it's only words; I think you'll know the figure. It isn't always on somebody's tax return; that's why they want you to tell 'em.
Quote from the revenue website:
Who can receive gross payments under CIS?
If you run a business that meets certain conditions, you can ask us to register you for gross payment. Your business must:
do construction work in the UK and be run largely through a bank account
have a construction turnover, excluding VAT and the cost of materials, of at least �30,000 each year (more for partnerships and most companies)
have complied with all its tax obligations
Before we can grant you gross payment status so you can get paid with no deductions, you'll need to show us that your business passes three tests.
Business test
You'll need to show us that your business:
carries out construction work - or provides labour for construction work - in the UK
is run largely through a bank account
Turnover test
We'll look at your business turnover from construction work for the 12 months before you apply for gross payment status. Ignoring VAT and the cost of materials, your construction turnover must be at least �30,000 if you're a sole-trader