How often can you test for a higher dan on the black belt?

You may test for your second dan one year after receiving for you first dan.

You may test for your third dan two years after receiving your second dan.

You may test for your fourth dan three years after receiving your third dan.

You man test for your fifth dan four years after receiving your fourth dan.

You may test for your sixth dan five years after receiving your fifth dan.

You may test for your seventh dan six year after receiving your sixth dan.

You may test for your eighth dan seven years after receiving your seventh dan.

You may test for your ninth dan eight years after receiving your eighth dan.