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Most teachers even in MATS are on burgundy book conditions
The vast majority of publicly funded schools in England operate according to the provisions of the Burgundy Book - conditions of Service for Teachers in England and Wales which specifies the notice periods for teachers in local authority maintained schools.
Typically, you would be expected to give two months’ notice, and in the summer term three months’ notice, in order to leave your post at the end of the term.
Inclusive of school holidays, broadly speaking, the dates of the three English school terms run from the following dates:
for the autumn term, from 1 September to 31 December;
for the spring term, from 1 January to 30 April; and
for the summer term, from 1 May to 31 August.
Therefore, if you wish to leave your job, you would be expected to give notice by the following dates:
to leave at 31 December, give notice by no later than 31 October;
to leave at 30 April, give notice by no later than 28 February; and
to leave at 31 August, give notice by no later than 31 May.