It depends on the size and condition of the tree. Generally, a dead tree can remain standing for several years without any major issues. However, as time passes, it becomes increasingly more dangerous due to potential decay or weakened branches that could fall unexpectedly. It is important to have an experienced arborist inspect your trees regularly in order to identify any potential hazards before they become a problem. If you suspect a dead tree may be present on your property, contact a local tree service company right away for professional advice and assistance with removal if necessary.