Only three fields must be mapped, because only three are needed to depreciate anything: what the asset is, when it went into service, and what it cost.
They sit in a strip above the table with their current state:
REQUIRED ✓ Asset description/name (required) ✓ Date placed in service (required) ⚠ Original cost/basis (required): not mapped Showing first 50 of 214 rows
A green chip means it's mapped. A red one is clickable: it scrolls the table to the column most likely to be the one you want and puts focus there. On a file with sixty columns, that's the difference between a moment and a hunt.
Where this is in the app
Dashboard → Import assets — or, from a return, Assets tab → Add assets → Bulk import
The strip sits above the mapping table on the Map Columns step of the import. See Mapping columns, and what the step does.
Why so few
Everything else is optional by design. A file that carries only the three still imports and still computes. The rest of the fields exist to carry over what your previous system knew, not to interrogate you.
Prior depreciation is the one worth seeking out. Without it, an asset part-way through its life starts over.
Mapped is not the same as valid
The strip tracks whether a field has a column pointed at it, not whether that column's contents are usable.
A date column mapped to Placed in Service still has to contain dates. That's checked at the next step, on the rows themselves, where a bad value can be shown to you in context.