Dependent applications, document sourcing and translations, and the months of reduced income before the spouse is working. Add relocation, deposits and childcare. Ask whether professional support for the dependants is quoted separately from the principal's case or bundled into one figure.
Budget the single-income period first
The largest number in this kind of move is often the earnings gap rather than professional fees. Model a realistic gap and a longer one, and decide in advance what the family does if the longer version happens. Then ask for an itemized scope covering dependent preparation and any follow-up questions.
Confirm official charges at the time of each step rather than relying on a figure quoted at the first meeting. Hypothetical example: a household whose accompanying spouse is a commercial insurance broker budgets for a four-month single-income period and experiences nine. A first review would model both the expected gap and a materially longer one, and would ask what the family would actually do in the longer case: draw on savings, delay the move, or send the principal alone initially.
Deciding that in advance is a fifteen minute conversation; deciding it in month seven is not. Ask for dependent preparation to be quoted separately so the second half of the plan has a visible price.