<Can I deduct more then 3000 dollars of realized short term losses against let's say 20000 dollars in long term realized gains during the same tax year? IOW if I have 10000 in ST losses and 20000 in LT gains, will my liability be 10000 or 17000?>
AFAIK, the answer is yes. You can deduct more than $3000 of ST losses from $20,000 LT gains. In your example, your liability will be $10,000. The $3,000 only comes into play if you have net losses more than $3,000. If your net losses (losses - any gains) are more than $3,000, then you can only deduct $3000 and carry over any left over amount to future years.
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