I have finished and submitted my tax return for 2018. How can I use the software to start planning 2019 and changes I might see in my deductions or additional income?

[VolvoGirl · Accepted solution]

You can’t do that in the Online versions.  So do not change anything or you will overwrite your 2018 return.  Or are you using the Desktop installed program?

If you have the Desktop program you can do a What-If worksheet.  
Go to Forms Mode, click Forms in the upper right or on the left for Mac. Then click Open Forms box in the top of the column on the left. Open the US listing of forms and towards the bottom find the What-if worksheet. It's right under Estimated Taxes.  

Or start a new return to test in.  In the Desktop program you can save your return with another name to test in.

[shannonM3]

WOW VolvoGirl...What A Rock Star!!! Thank you so much for your quick answer (in under 2 minutes) and for all the great detail!! Yes, I am using the online version, so your comment/warning is PERFECT and very much appreciated!!