You will have to amend your 2017 tax return to add the Nonbusiness Energy Property Credit for the HVAC that was installed and paid for in 2017.
See this TurboTax support FAQ for amending a 2017 tax return originally completed and filed using the online editions - https://ttlc.intuit.com/questions/4252204
To enter Home Energy Credits -
- Click on Federal Taxes (Personal using Home and Business)
- Click on Deductions and Credit
- Click on I'll choose what I work on (if shown)
- Under Your Home
- On Home Energy Credits, click the start or update button
Or enter home energy improvement in the Search box located in the upper right of the program screen. Click on Jump to home energy improvement
On the screen Tell Us How Much You Paid for Energy-Saving Improvements -
For HVAC, electric heat pump water heater, natural gas, propane, or oil water heater, and a stove that burns biomass fuel to heat your home or heat water. Enter the cost in the box labeled Energy-Efficient Building Property.
