"Can a capital loss from a trust be entered on K-1 line 4a if it is not a final?"
No. To the extent that capital losses exceed capital gains, all such losses are
allocated to the fiduciary (the trust).
Capital losses may be carried forward indefinitely and those that have not been used can be passed through to the beneficiaries in the trust's final year. See Treas. Reg. § 1.642(h)-1
