Duplicate management capacity is the main item: paying someone overseas to hold responsibility the principal used to provide. Add return travel, cross-border accounting, and the record keeping needed to evidence continuing foreign activity. Legal and document costs sit on top and should be scoped separately.
Decide how long you can carry both
Model the period during which the foreign entity pays for management it previously received free, and confirm the business can sustain it beyond the first year. Ask counsel to itemize the assessment, drafting, dependent work and any later evidence responses, and to say what falls outside the quoted scope. Confirm official charges at the time of each step, and stress-test a plan that only works on schedule.
Add a figure most plans omit: what it costs the foreign business to be run by someone new. The successor will make different decisions, some of them worse for a period, and the difference is a real cost even though no invoice records it. Where the principal expects to remain involved remotely, price that time too, because it is drawn from the hours the new role needs.
Hypothetical example: a theatrical production company's founder budgets a successor's salary and the professional fees, then finds the largest cost in year one is a season programmed more cautiously than they would have programmed it, which is neither anyone's fault nor something the budget anticipated. Naming it in advance turns a disappointment into a planning assumption.