CISR12210 - The Scheme: contractors: review of business accounts
When you receive accounts or a return for a business that is not already treated as a contractor, you should examine the return or accounts to see whether the amount spent on construction operations is now enough for the business to be considered a deemed contractor (See CISR12050). This is in order to identify clear-cut cases.
Time need not be spent on detailed examination of cases which are only likely to be near the £1 million average threshold. Businesses whose annual expenditure fluctuates marginally above and below the limit should not be required to operate CIS.
If you conclude that a business should be classified as a deemed contractor as a result of this examination, you should consider the guidance at CISR12060 to establish when the business should be required to operate the Scheme.