A small construction company with three active sites at the same time put the problem to me bluntly: "I have crews rotating between sites, none have an office, and half the lots don't even have a decent cell signal. How do I know who entered, at what time, and where?". The paper timesheet signed by the foreman doesn't hold up to an IERIC inspection or a labor lawsuit. Here I explain how attendance control for construction staff is regulated in Argentina, what the special construction regime requires, and how to solve on-site clocking when there is no office or stable internet.