If I order the TURBOTAX DELUXE TAX YEAR 2017 WIN DOWNLOAD can I start putting in my 2017 tax data to get an idea of what my tax liability will be?

[xmasbaby0]

Of course you can.  When you use the desktop software you can prepare as many returns as you want--it is just that you can only e-file up to 5.  You can "play around" or use "what-if's" using the desktop version to get estimates.  Just make sure the return you file has all of the accurate and complete information, most of which will not become avialable until the end of January/early February from employers, banks, brokers, Social Security, etc.