Where do I start if I have never filed a US tax return?
With facts, not forms. Four of them decide the shape of everything that follows: how your US citizenship arose and what document proves it, where you were living in each year that is unfiled, whether you have any US income or connections at all, and how the failure to file came about. The route available to you depends on whether that failure was non-willful and on where you live, so those facts are not preliminaries — they are the decision. Only once they are settled does it make sense to ask which years are in scope and which accounts have to be reported for them.
Which comes first, the back returns or the foreign account reports?
Neither goes first on its own. The relief route decides which years of returns and which years of account reports are in scope, and they are prepared and submitted together, because the relief attaches to the submission as a whole rather than to each piece of it. That is why sending in whichever document you happen to be able to complete is the wrong instinct, however diligent it feels. The practical order is: establish the facts, pick the route, assemble the returns and the account reports the route calls for, then submit them as one package.
How do I show I did not know I had to file US taxes?
By recording what actually happened, in dates. When you left the United States and how old you were, where you have lived and worked since, what passport you have travelled on, whether anyone — an employer, a bank, a family member, an adviser — ever raised the subject, and what brought you to look into it now. Non-willfulness is a conclusion drawn from facts like these rather than a statement you make about yourself, so the work is documentary. A plainly told, dated account supported by records is far stronger than any assertion of good faith.
Do I need my parents' paperwork to sort this out?
Usually you need very little of it, but the little you need matters. The birth record is the document that establishes the citizenship the whole file turns on, and the dates around the family's departure help fix where you were living in the early unfiled years. Beyond that, what your parents did or did not file has no bearing on your own position. People often delay starting because they imagine a family archive is required. In practice it is one birth document, a record of where you have lived, and then your own income and account information for the years in scope.
Can I stop the clock while I get organised?
Nothing stops by waiting, and the exposure in these files sits on returns and account reports that were not filed, so it simply continues to accumulate quietly. What waiting does cost you is control. The relief routes are written for people who come forward, so the value of starting is not speed for its own sake but keeping the choice of route in your hands. The sensible response to feeling unprepared is therefore to establish the facts and pick the route quickly, then take whatever time the record gathering honestly needs.
What if the IRS contacts me before I have filed anything?
Then the position changes, because these routes exist for people who come to them rather than for people who are found. Contact does not make the situation hopeless, but it narrows what is available and it makes the sequence of what you do next much more consequential. The first step in that case is not to reply off the cuff or to rush a return in. It is to establish exactly what has been asked, what year it concerns and what your position for that year actually is, and then to decide the order of filings from there.
What is a dual-status alien?
Someone who is a US tax resident for part of a year and a non-resident for the rest of it — almost always the year of arrival or the year of departure. You file one return covering both periods, with worldwide income and ordinary deductions for the resident part and US-source income under the non-resident rules for the other. Several ordinary reliefs, including joint filing, are restricted for the year. See dual-status alien.
What is a "dual-status alien spouse", and why is my software asking?
The question comes from the filing-status screens, and it is asking whether your spouse was a non-resident or part-year resident for the year — because if they were, a joint return is not available by default. An election exists to treat a non-resident spouse as a resident for the whole year, which unlocks joint filing at the price of bringing their worldwide income into the US return and their accounts into its reporting. See a US person with a non-resident spouse.