Business & farm

Form 8990's utility for a Personal Form 1040 is probably close to zero if not zero. 

The specific question goes to the point that the Taxpayer has received a Schedule K-1(1065) from a PTP/MLP with entries on the K-1 possibly including on Line 13 Code=K Excess business interest expense. Note that entry in TurboTax Personal the support for Schedule K-1(1065) line 13 with Code=K is noted as unsupported.  Further note, that the Form 8990 would be filed by the MLP.  However, as you can read the following, it is all most likely irrelevant since the excess business interest expense deductibility is severely limited to businesses as described below.

• https://www.irs.gov/forms-pubs/about-form-8990
  
  
• The Tax Cuts and Jobs Act (P.L. 115-97) amended section 163(j) to reflect a limitation on the deduction for business interest expense for certain taxpayers in tax years beginning after 2017.  

• Background.  For tax years beginning after Dec. 31, 2017, for certain taxpayers, the deduction allowed for business interest for any tax year can’t exceed the sum of: (1) the taxpayer’s business interest income for the tax year; (2) 30% of the taxpayer’s adjusted taxable income (ATI) for the tax year; plus (3) the taxpayer’s floor plan financing interest (certain interest paid by vehicle dealers) for the tax year. (Code Sec. 163(j)(1)) Disallowed business interest may be carried forward indefinitely, subject to certain restrictions applicable to partnerships.

  In November 2018, IRS issued proposed regs on the new business interest deduction. For coverage of the proposed regs, see here for the rules for C corporations, here for the rules for partnerships and S corporations, here for the small taxpayer exemption and relation to other interest provisions, here for the election for excepted trades or businesses and the REIT safe harbor, and here for the rules for foreign corporations and shareholders and foreign persons with effectively connected income (ECI).