Answered by Shaykh Faraz Rabbani
Walaikum assalam wa rahmatullah,
I pray that you are well and in the best of spirits.
The holiday pay is part of your 12-month contract, which basically entails 10 months of teaching and grants you 2 months of vacation.
As such, there is nothing wrong, Islamically, with terminating the contract after the holidays in a way acceptable within the terms of the contract and customary practice in schools.
And Allah alone gives success.