Lancashire: Paul Greenall, who was elected for the Conservative Party in West Lancashire East division, has left the party to sit as a non-aligned county councillor.
Colchester: Shrub End ward, after the resignation of Liberal Democrat councillor Karen Chaplin. Term ends 2019.
East Cambridgeshire: Ely South ward, after the resignation of Conservative councillor Tom Hunt, who has taken a politically restricted post with the Mayor of Cambridgeshire and Peterborough. Term ends 2019.
Highland: Tain and Easter Ross ward, after the resignation of Liberal Democrat councillor Jamie Stone, now Member of Parliament for Caithness, Sutherland and Easter Ross. Term ends 2022.
Dates for byelections
Aberdeenshire: The byelection due in Inverurie and District ward will be held on 12 October.
Glasgow: The byelection due in Cardonald ward will be held on 7 September.