Partner Outside Basis & Shareholder Basis

Basis in a pass-through entity is the owner's tax investment in the interest, and it performs three functions: it limits the amount of loss the owner may deduct, it determines whether distributions are tax-free returns of capital or taxable gain, and it establishes the amount of gain or loss recognized on disposition of the interest.

Outside basis - the owner's basis in the entity interest - is distinct from inside basis, the entity's basis in its own assets. A partner's outside basis begins with the cash and adjusted basis of property contributed, increases for the partner's share of income and additional contributions, and importantly increases for the partner's share of partnership liabilities under Section 752, since debt-financed activity is treated as though the partner contributed the borrowed funds. It decreases for distributions, the partner's share of losses and nondeductible expenses, and reductions in the share of liabilities.

S corporation shareholder basis follows similar mechanics with a critical difference: entity-level debt does not create shareholder basis. Only direct loans from the shareholder to the corporation do, and shareholders maintain separate stock basis and debt basis with a defined ordering for loss absorption and restoration. This distinction routinely surprises clients who convert from an LLC to an S corporation and lose the ability to deduct losses funded by entity borrowings.

Losses in excess of basis are suspended and carried forward until basis is restored. Beyond the basis limitation, deductibility must also clear the at-risk rules under Section 465 and the passive activity loss rules under Section 469, applied in that order. Basis tracking failures are among the most common and most expensive errors in pass-through practice, because reconstructing basis across many years of returns after the fact is laborious and frequently produces adjustments on examination.