I got K1 with box 16 marked (meaining K3 attached) but no K3 came and was told that K3 will be available in August. what should I do not to delay the tax finding ?

You can uncheck box 16 and file your return.  The IRS has provided additional information in regards to the K-2 and K-3 forms filed by certain businesses for tax year 2021.  Please see K-2 and K-3 FAQ for additional information.

the IRS has waived k-3 reporting for 2021.  the problem comes about if that k-3 reports foreign tax credits. there really isn't a way to claim those credits without the form. however, in many cases, there will be no FTC. your options are to file by 4/18/2022 and amend if there is FTC or file an extension and wait for the partnership to provide the k-3 info. To file now uncheck the k-3 box on the Turbotax k-1 form.

Do you recommend unchecking Box 16 or filing an extension?