The worst moment to look for a model number is when the thing has already broken, usually in the dark, usually with a phone torch, usually behind something heavy.
Five fields, written down once while the appliance is working and accessible, remove that moment permanently. It takes about two minutes per item and it is the highest return household admin there is.
The five fields
5 things to do
Ticks are for this visit only. Nothing here is saved anywhere.
Where the model number usually hides
It is almost never on the front. Fridges hide it inside near the salad drawer, washing machines around the door opening, dishwashers on the edge of the door where you only see it with the door open.
The full list by appliance type, including what to do when the label has worn away, is in how to find the model number on any appliance.
Why the serial number matters more than you expect
A model number tells a supplier which part fits. A serial number tells a manufacturer which production run yours came from, which matters for warranty claims and for recalls.
Recalls are the underrated one. Manufacturers issue them regularly and reach owners through registration, which most people skip. If you have the serial number written down somewhere findable, you can check it against a recall list in a minute.
Photograph the plate rather than transcribing it
Model numbers are long, and they mix letters and digits in ways that are easy to get wrong in bad light. A photograph of the plate takes a second and is always right.
Keep the photograph, but also type the model number somewhere searchable, because a photo buried in three years of camera roll is not findable when you need it.
The best moment to do this is a move
Every fact about a house passes through your hands in the two weeks around moving in, and almost none of it gets written down. Meter readings, which utility is with whom, where the stopcock is, what came with the property.
A year later the boiler needs servicing and nobody remembers who installed it. Recording it while it is in front of you takes minutes and saves an afternoon.