Does every spoiler need homologation?

If the part is homologated directly for your model and installed per the manufacturer's instructions, a separate registration usually isn't needed. For unmarked parts or larger body modifications, registration is required.

What does the inspection check on body addons?

Mainly the strength of the mounting, the absence of dangerous sharp edges and protrusions, and that the part doesn't cover mandatory features like lights, the license plate, or reversing sensors.

Spoilers and body addons — legality and safe installation

Spoilers, side skirts, diffusers, and similar addons are among the most visible modifications, but they're subject to rules too — mainly for the safety of pedestrians and other road users.

What makes an addon legal

The part should be homologated for your specific model and installed per the manufacturer's instructions. If homologation is missing, or the part affects the vehicle's dimensions beyond a normal tolerance, a technical assessment and possibly a registry entry are required.

What to watch out for

Sharp edges and protrusions — the decree requires that exterior parts of the car have no dangerous sharp edges that could endanger pedestrians; amateur-modified or cut-down addons often fail to meet this requirement.
Mounting strength — an insufficiently secured spoiler or side skirts can come loose while driving; the inspection checks mounting stability.
Covering mandatory features — an addon must not cover lights, the license plate, reversing sensors, or other mandatory equipment.
Combination with a lowered suspension — for low-sitting diffusers and side skirts, check ground clearance after any suspension lowering, to avoid scraping the road.

Recommendation

For visibly non-original parts without homologation, have the installation assessed at an inspection station before final mounting — adjustments are easier to handle before registration than after.