Can I use short-term losses to offset my long-term gains?

Yes. The IRS nets your gains and losses by category first: short-term losses cancel short-term gains, and long-term losses cancel long-term gains. Then, if one bucket still has a net loss, it crosses over to offset the other bucket's net gain. So a short-term loss can wipe out a long-term gain, and vice versa. If a net loss remains after all the netting, you can deduct up to $3,000 against ordinary income and carry the rest forward. Because short-term gains are taxed at higher ordinary rates, it's usually most valuable to aim your losses at short-term gains first, but the netting rules handle the ordering for you on Schedule D and Form 8949.