Possibly, and this is the CIS trap that catches businesses who have never thought of themselves as construction. If your business is outside construction but your spend on construction operations exceeds £3 million in any rolling twelve-month period, you become a deemed contractor and must operate CIS on payments to subcontractors like any builder. It applies to property investors, large landlords, retailers doing a fit-out programme, manufacturers extending a site. The rolling twelve-month test means it can arrive unannounced during a big project. Once in, you must register, verify subcontractors, deduct, and file monthly returns, with the same £100-a-month penalties. There are exclusions for work on your own premises for your own use, which is where careful analysis pays.