Provide relevant status approvals, admission and departure records, work history and evidence of periods outside the United States. Identify missing records and uncertain dates.
Keep categories and physical presence clear
Distinguish principal work status from dependent status and identify role changes. Do not assume all entries bearing an H or L label receive the same treatment. The calculation should follow the actual individual record.
Gather them in order of how hard they are to obtain, because the slowest item sets the date the review can begin. Government records of admission and prior approvals usually arrive first and fastest; employer records — assignment letters, payroll by jurisdiction, internal transfer notices — take longer and often need a request routed through a former manager who has since moved on. Boarding passes, tenancy records and school registrations abroad are the slowest of all, and they are exactly what fills a disputed gap, so request them at the outset rather than when the gap appears.
One caution about tidy summaries: a spreadsheet produced by a corporate mobility team is a useful index and is not evidence. Keep every figure in it traceable to a document and, where a cell cannot be traced, flag it and say so, because an unsourced number inside an otherwise documented analysis draws attention to everything around it.