Why is the tax liability zero? Married-File-Jointly 2017 fed tax was $2K but 2018 Federal tax is $0. We used form 5695 for 2018 Solar Tax Credit.

[weidass]

Seems that the tax liability is incorrect.  With similar total income with similar deductions between the two years.  Differences were the Energy Tax Credit for new Solar Installations, Capital Gains of $15K, and new rental property with a $8k loss.

[MarilynG · Accepted solution]

Don't forget that the new Standard Deduction for 2018 for a couple Married Filing Jointly is $24,000, rather than $12,000 as in 2017 (more if over 65).

The Rental Property Loss and Energy Tax Credit could have also made a difference.

In FORMS mode (upper right corner), you can view your Form 1040 and related Schedules.  

Click the Magnifying Glass to the left of amounts on a form you are viewing to jump to the related worksheet (screenshot).