Stobhill ward member Rachel Moore has resigned from Morpeth Town Council.
The vacancy will be advertised by the authority for 14 working days in the ward and on the noticeboard at Morpeth Town Hall.
Residents in Stobhill have until February 1 to submit a letter to the elections office to request that a by-election takes place. Details on how to do this will be on the notice.
A by-election will be organised if 10 or more letters are submitted.
If this does not happen, the co-option procedure will come into effect.