form 4684 instructions answer your question as to when to claim the loss and the form (section B) needs to be filed to claim your casualty loss. if you have difficulties completing it you may want to consult a tax professional or use Turbotax Live
(abbreviated from 4684 instructions)
The loss is not sustained until you know with reasonable certainty whether reimbursement will be received. You got the check in 2024 so you know for certainty in that year.
**********************
what is the amount of your loss?
This involves knowing the fair market value of the property before and after the loss.
