The parts that are the same everywhere.
Eleven things about a divorce that federal law decides, so the answer does not change when you cross a state line. Each one read off the statute, the regulation or the agency’s own publication, and linked to it.
Everything else on this site is state law, which means fifty different answers and fifty different statutes. These eleven are federal. The rule in Alaska is the rule in Alabama, it is written down, and we quote it rather than describe it — because on every one of these subjects the version repeated most often is the wrong one.
None of them look federal from the outside. They arrive as “can I stay on his insurance”, “who claims the children”, “does she get my pension”. So they are grouped below by when the question turns up, not by which agency owns the answer.
Before anything is signed
These decide how much of the rest matters, and two of them have deadlines that start running the day the marriage ends rather than the day you get round to it.
The money
Two of these are worth more than the house, and both are routinely got wrong by people who are trying hard to get them right.
When your situation has another layer
Each of these changes the answer to almost everything else, and each is covered badly nearly everywhere.
What federal law does not decide
Whether you get divorced, on what grounds, how the property is divided, whether there is alimony and how much, and what happens with the children — all of that is state law, and it is genuinely different from state to state. Federal law sits on top of it: it decides how a pension is actually split once a state court has ordered it, what the tax consequence is, and which state gets to decide in the first place. Both halves matter, and a page that only knows one of them will get you to the wrong answer confidently.
Now the part that is different everywhere
Filing rules, court fees, child support, custody and alimony — fifty states, each read off its own statute.