Outlook:
The following forward-looking measures and the underlying assumptions involve significant known and unknown risks and uncertainties, including those described below, and actual results may vary materially from these forward-looking measures. We do not provide guidance for operating income or diluted net income per share attributable to DaVita Inc. on a basis consistent with United States generally accepted accounting principles (GAAP) nor a reconciliation of forward-looking non-GAAP financial measures to the most directly comparable GAAP financial measures on a forward-looking basis because we are unable to predict certain items contained in the GAAP measures without unreasonable efforts. These current non-GAAP financial measures do not include certain items, including gains on changes in ownership interest and foreign currency fluctuations, which may be significant. The guidance for our effective income tax rate on adjusted income attributable to DaVita Inc. also excludes the amount of third-party owners' income and related taxes attributable to non-tax paying entities.
Additionally, in connection with a comment letter from the Securities and Exchange Commission Staff, beginning in the second quarter of 2024, we no longer exclude center closure costs from our 2024 guidance. Accordingly, under the revised presentation, our current 2024 guidance no longer excludes approximately $60 million in center closure costs. Prior 2024 guidance shown below is as of May 2, 2024, and therefore is shown under the prior presentation methodology.
| Current 2024 guidance | Prior 2024 guidance | ||||||
| Low | High | Low | High | ||||
| (dollars in millions, except per share data) | |||||||
| Adjusted operating income | $1,910 | $2,010 | $1,875 | $1,975 | |||
| Adjusted diluted net income per share attributable to DaVita Inc. | $9.25 | $10.05 | $9.00 | $9.80 | |||
| Free cash flow | $950 | $1,200 | $900 | $1,150 | |||