My return was short about 1400 bucks need to find out why what do i do?

the IRS should be sending you a letter explaining the difference. normally this takes 2-3 weeks.  these are not normal times.  your only other option would be to call the IRS

800-829-1040

First choose your language.

Then 2

Then 1

Then 3

Then 2

When asked for SSN  do nothing it will ask twice

Then 2

Then 4

the IRS phone lines are extremely busy presently.  you may not get through so you'll have to keep trying or wait for the letter 

One common thing a number of folks are experiencing if they claimed a Recovery Rebate Credit on their return for a stimulus payment (1 and 2) they had actually already received , or if they received a stimulus payment (1 and 2) after filing.  Or if the IRS adjusted the amount of that credit for some other reason.

You can tell if you claimed a Recovery Rebate Credit by looking at Line 30 of your Form 1040.

 

Also check the IRS "Where's My Refund" tool.  Sometimes there is a message there when they make a change, such as an offset.

https://www.irs.gov/refunds

 

Also, if you are expecting a state refund, it comes separately.  So don't go by any total refund amount that is a sum of Federal and state refunds added together.   TurboTax provides a summary figure that can be confusing.  For the Federal refund amount you submitted, go by what is on your Form 1040, Line 35a.