The takeaway
The Road Safety Authority says a car’s windscreen and front side windows must let at least 65% of light through for the National Car Test (NCT). It also says drivers need enough front and side visibility to drive safely.
This guide covers ordinary private passenger cars in Ireland. Northern Ireland has separate guidance. Imports, historic vehicles, taxis, commercial vehicles and unusual glazing need a separate check.
Check the finished front windows
The NCT Manual, section 3.2, lists transmission below 65% as a major deficiency for the windscreen, relevant internal panes or partitions, and front side windows needed for driving.
If the tester suspects excessive tint, the manual calls for a calibrated light-meter check. Ask for the glass-and-film reading; a film label alone is insufficient.
The meter’s stated accuracy is not a lower tint target.
Rear windows and sun strips
The RSA tint guidance says rear-window tint alone does not fail the roadworthiness test. Other glazing, mirror and visibility checks still apply under the NCT Manual.
The RSA's line-of-vision guidance warns that a tinted sun strip extending below the tips of the wipers can obstruct the driver's view and cause an NCT failure. It does not establish an approved strip size for your car; check before fitting one.
A doctor's letter and the NCT
The RSA says a doctor’s letter does not create a medical exemption from the NCT tint check.
Before you book
Keep the product and installation details. Get vehicle-specific advice before adding film to unusual or already-dark front glass.
An NCT certificate records a basic roadworthiness check at the time of the test. The car must remain safe afterward.
Sources checked 18 October 2026. This is a scoped explanation of current RSA guidance and its linked NCT Manual, not a complete current statutory audit, legal advice or approval for a particular installation. The U.S. tint planner does not determine Ireland's requirements.