This is the whole list, for a retirement move from the UK. It is built from the same catalogue our free planner uses, so nothing on it applies to somebody else’s country and nothing that applies to yours is missing.
40 steps, grouped into the five phases of the move

Since Brexit a British retiree needs a visa — usually the non-lucrative visa — applied for from the UK before moving. State pensioners can normally still use the S1 for healthcare.
Nothing here is compulsory and nothing is in a fixed order. Timings are the usual ones — your own dates depend on when you are moving.
Is Spain right for you, and whereabouts?
Narrow the whole country down to two or three places worth visiting.
When: 36–12 months before the move
What your life will actually cost, line by line.
When: 30–12 months before the move
The legal, tax and healthcare route — and what happens to your home.
Which permit lets you live in Spain, and what each one asks of you.
When: 18–9 months before the move
The number the consulate will measure you against, and what counts towards it.
When: 18–9 months before the move
Criminal record check, medical certificate, insurance — each with its own clock.
When: 6–3 months before the move
The appointment itself, and what happens in the weeks after it.
When: 5–2 months before the move
The rule that decides which country taxes your worldwide income.
When: 18–6 months before the move
What actually lands in your account each month, after Spanish tax.
When: 18–6 months before the move
Which country gets to tax what — and how you avoid paying twice.
When: 18–6 months before the move
Modelo 720: a declaration, not a tax — but one with real deadlines.
When: Around the move itself
Ending your tax residence at home is a separate job from starting it in Spain.
When: 9–1 months before the move
Four routes into cover, and which of them are open to you.
When: 18–6 months before the move
Not any policy — the specific kind a consulate accepts.
When: 6–2 months before the move
Arrive with your history in your hand rather than in another country’s system.
When: 3–0 months before the move
The cost of a transfer is mostly hidden in the rate, not the fee.
When: 12–1 months before the move
Drawing, transferring, or leaving it where it is — while you can still take advice at home.
When: 18–6 months before the move
You will need one for almost everything, and it is easier with an NIE.
When: Around the move itself
Spanish succession rules can apply to you unless you say otherwise.
When: Around the move itself
Sell, let, holiday-let or keep. The biggest single decision of the move.
When: 18–9 months before the move
Winding things up and packing them off.
Three surveys, and ask what is not in the price.
When: 9–4 months before the move
The cheapest thing you can do to a removal quote is make it smaller.
When: 9–3 months before the move
Importing is possible, and it is rarely as cheap as it looks.
When: 9–3 months before the move
Apostille first, then sworn translation. The other way round means paying twice.
When: 6–2 months before the move
The week between leaving and arriving needs a plan of its own.
When: 3–1 months before the move
Everything that renews automatically, found before it renews from Spain.
When: 1–0 months before the move
For a year, not a month. The important letters come annually.
When: 1–0 months before the move
The month around the move is when most policies quietly stop applying.
When: 2–0 months before the move
The journey, and your first weeks in Spain.
The card that proves your residence, and there is a deadline from the day you land.
When: 0–1 months after the move
Your Spanish tax and identity number. Nothing works without it.
When: 0–1 months after the move
The local register. Free, quick, and required for almost everything else.
When: 0–1 months after the move
Most people who rent for a year first are glad they did.
When: Around the move itself
Straightforward once you have an NIE and a Spanish bank account.
When: 0–1 months after the move
Turn your entitlement into an actual doctor with an actual appointment.
When: 0–2 months after the move
Closing the loose ends and renewing what needs renewing.
The one to pay for advice on. Later ones are much easier.
When: 3–15 months after the move
There is a deadline, and what happens at it depends on where your licence is from.
When: 1–6 months after the move
A short document that saves your family a long process.
When: 3–12 months after the move
The thing that decides whether you live in Spain or beside it.
When: 0–12 months after the move
The part of the move that decides whether you stay.
When: 1–12 months after the move
The first renewal comes round faster than you expect. Start early.
When: 9–12 months after the move
Same list, with your dates on it, the steps that don’t apply to your household removed, and a note of what to do next. Free, and every question can be skipped.
The professionals these steps usually need, in Spain and where you are now.