If you already filed your 2024 tax return with an itemized deduction for the full amount of a medical expense, and you later receive a reimbursement for part or all of the expense, then the reimbursement is what's called an itemized deduction recovery. You do not amend the 2024 tax return that you already filed. You have to report the itemized deduction recovery as income on your tax return for the year that you received the reimbursement, but only to the extent that you actually received a tax benefit from deducting the amount that was later reimbursed. That gets you into a complicated calculation. But this does not seem to be your case. If I understand correctly, you have not yet filed your 2024 tax return, so if you are claiming medical expenses on your 2024 tax return, you can simply claim only the amount that was not reimbursed.
Note that on your federal tax return none of this matters unless you are claiming itemized deductions for 2024 instead of the standard deduction, and your total deductible medical expenses are more than 7.5% of your Adjusted Gross Income (AGI). It might matter on your state tax return if your state allows a deduction for medical expenses with a lower threshold.
