I am doing well in the stock market this year with short term trading. In the past I had losses. Can these losses be carried forward to this year? And how far back?

[Hal_Al · Accepted solution]

Yes, past year(s) losses are carried forward and can be used against this year's capital gains (long or short term),

How far back? All the way. If you have been doing it correctly, you should have been reporting losses on your tax returns, in the past, and the carry over from 2016 will already include all allowable losses from all past years.

if you did not report losses, in past years, seek professional help in determining the carry over for 2017. Amended returns for years 2014, 2015 and 2016 will most likely be required.

[VolvoGirl]

Have you reported all the losses before?  If you have investment sale losses, after you subtract the losses from your gains you can only deduct up to 3,000 per year. You can only deduct up to 3,000 (1,500 MFS) loss per year after any gains you have.  So if you have a lot of current gains you can use up the loss.  The rest you will have to carryover until it is used up.

If you transferred your prior return info it should already be filled in.