CIS is a UK rule, but most software treats it as a finance add-on. The site team mobilises a plastering gang on Monday without knowing verification status because CIS lives in a spreadsheet the site manager never opens.
SiteOS keeps CIS status on the job and across the company subcontractor list. Amber before mobilisation. Statements and verification sit next to the diary and POs that caused the spend.
That matters when HMRC asks questions, but it matters more on a wet Tuesday when someone turns up and the gate needs a straight answer.
One company price means site, office and QS all see the same record without rationing logins. CIS is not a bolt-on module you discover at month-end.