Insurance companies frequently refuse to replace child safety seats after an accident. Typcially, they will tell you the seat does not appear to be damaged or they are only obligated to replace the seat if the child was in the vehicle at the time.
California Insurance Code § 11580.011 requires the replacement of a child passenger restraint system damaged due to an accident. A visual determination that the seats exhibit no signs of damage is insufficient grounds to refuse replacement.
Also, the NHTSA recommends replacing child safety seats after any non-minor collision. The NHTSA defines a minor collision as one that meets ALL of the following criteria: the vehicle was able to be driven away from the crash site; the vehicle door nearest the safety seat was undamaged; there were no injuries to any of the vehicle occupants; the air bags (if present) did not deploy; and there is no visible damage to the safety seat.
In addition, most car seat manufacturers recommend replacement following a collision even if there appears to be no damage to the car seat on the surface, because the impact and force of a collision can cause unseen structural damage to the car seat which may prohibit the car seat from properly protecting your child in the event of a sudden stop or crash.