Per Form 706 instructions,

 “Complete and file Schedule J if you claim a deduction on item 14 of Part 5—Recapitulation.”

 “You must complete and attach Schedule K if you claimed deductions on either item 15 or item 16 of Part 5—Recapitulation.”

In other words, if you did not claim any deductions on items 14, 15 or 16 of Part 5 – Recapitulation, you do not have to complete Schedules J and K.