TurboTax does appropriately apply the alternative calculation for the year of marriage in cases where it reduces the repayment of the premium tax credit. The form does not allow an override in instances where it does not provide a benefit. If you are higher-income yourself then it is unlikely the alternative calculation will yield a benefit.
If it does not seem to calculate correctly, you can make sure that you are selected as the primary policyholder on the 1095-A for the year of marriage calculation, not your spouse. You can also ensure that all the income in your tax return is correctly allocated to the spouse who earned it.
If you want to ensure the calculation is working correctly, you can switch your W-2 to your spouse's name or reduce the Box 1 federal income amount. That should make the marriage calculation kick in.
