i don't it's possible to have the excess of your "balance due" payment applied to your 2025 estimate.
normally the BD is paid
1)by mail with 1040-V which doesn't allow allocated
2) there's direct debit
3) you can pay online but there's no way to split the payment
finally it's safer to separate the payments if not and the IRS finds a mistake that increase your taxes. as one payment it would take it out of the estimate portion, leaving you potentially underpaid for the first quarter
there is a way to do what you want. make an extension payment by filing an extension either online or by mail. then in Turbotax list the estimated tax payment and in the estimate section have the overpayment applied to your 2025 estimate. NOT good practice since to do this you would have to overstate your 2024 tax liability on the extension. There is a question as to the validiatity of the extension if the tax liability is wildly off. Also, while not required, I would file the 1040 not sooner than 4/16
you could make separate payment online for your balance due and 2025 estimate.
