What the research says

Studies of children who are allowed to move ahead in a subject, by skipping a year or taking a class early, have mostly found that they do well, both in that subject and socially, when the move is planned with them.

The studies also find that it matters how it is done: one subject at a time, with a teacher who agrees, and with the child wanting it.

None of this is a label. A child can be far ahead in maths and right where you would expect in reading, and both are fine.