1.What you actually need to know
Withdrawing a child from school to homeschool sounds straightforward, but the legal requirements differ so much by country, state, or even local district that no single article can give you the full picture. What's a simple one-page letter in one place is a formal application with portfolio reviews in another. Getting this right matters — operating outside the rules, even accidentally, can create real problems.
The first step is always the same: find your jurisdiction's actual rules before you do anything else. In the United States, education law is set at state level, so the process in Texas looks nothing like the process in New York. In the United Kingdom, England, Scotland, Wales, and Northern Ireland each have separate frameworks. Australia hands responsibility to its states and territories. Canada, similarly, varies province by province.
Good places to start your research: your country or state's official education department website, or a well-established national homeschooling organisation. In the US, the Home School Legal Defense Association (HSLDA) maintains a state-by-state legal summary. In England, Education Otherwise has published guidance for families for decades. These organisations can point you to current requirements — check that whatever you're reading is up to date, since rules do change.
When you find your local requirements, look for answers to a handful of practical questions. Do you need to notify anyone formally, and if so, whom — the school, the local authority, the district? Is there a deadline or notice period? Are you required to submit a curriculum plan, and does anyone review or approve it? Will your child be assessed periodically? Is there a registration process with the state or local authority? Write down what you find, keep a copy, and note the date — this is the beginning of your record-keeping habit.