Which accounting principle must follow flow-through items in an S Corporation?

In the context of S Corporations, flow-through items refer to income, deductions, and credits that are passed directly through to the shareholders, rather than being taxed at the corporate level. The correct principle that governs these flow-through items is per-day, per-share accounting. This method ensures that income and deductions are appropriately attributed to each shareholder based on their share ownership and held period throughout the tax year.

This principle is critically important for determining each shareholder's tax liability accurately, as it reflects the proportional share of income and losses that each shareholder is entitled to report on their personal tax returns. This aligns with the concept of S Corporations being pass-through entities, where tax liability shifts to individual shareholders rather than the corporation itself.

In contrast, the other options do not specifically address how income and expenses are distributed among shareholders in an S Corporation context. Cash accounting and accrual accounting methods primarily pertain to how businesses recognize revenue and expenses at the corporate level, not the distribution of flow-through items to individual shareholders. Fixed accounting is not a recognized accounting principle in this context and doesn't apply to the treatment of flow-through items.