Please review Sec. 453(A)(c) to see if it applies to your situation with respect to the interest charge. (It  applies only when the year-end installment receivables balance from sales for more than $150,000 during the year exceeds $5 million. That's at the partner level.)

If does, per IRS Notice 88-81, the partnership is required to provide the partners with the information necessary to calculate the interest charge, usually by attaching a statement to their Schedule K-1.

If you need further assistance, please let me know.