Each joining spouse and unmarried child under 21 must be considered in the initial application, and each adds a separate US$15,000 processing fee and a US$1 million gift. Deciding to apply alone is therefore a decision about who is left out of that initial application, so it should be made deliberately rather than by default.
Decide the household before filing
List everyone who might realistically move — a spouse, a child approaching 21, a partner not yet married — and confirm their intentions before the application goes in. Ask a qualified adviser what options exist for a relative who is not included initially, rather than assuming a later addition is routine or cost-free. The financial difference is large: a solo case and a two-person case are separated by roughly a million dollars plus fees.
Two facts sharpen that decision. Each included family member is assessed on their own admissibility, so one person's record can affect the household outcome even where every payment has been made. And an unmarried child approaching twenty-one changes the calculation, because timing rather than intention may decide whether they can be included at all.
Hypothetical example: a retired equine-clinic owner intends to apply alone and bring an adult daughter across later, and the review's first task is to explain what separate routes, if any, exist for her, rather than letting the assumption stand unexamined.