From United States v. Textron, 2009 U.S. App. LEXIS 18103 (1st Cir. Aug. 13, 2009) (en banc):

The question for the en banc court is whether the attorney work product doctrine shields from an IRS summons "tax accrual work papers" prepared by lawyers and others in Textron's Tax Department to support Textron's calculation of tax reserves for its audited corporate financial statements. ***

As a publicly traded corporation, Textron is required by federal securities law to have public financial statements certified by an independent auditor.... To prepare such financial statements, Textron must calculate reserves to be entered on the company books to account for contingent tax liabilities. Such liabilities, which affect the portrayal of assets and earnings, include estimates of potential liability if the IRS decides to challenge debatable positions taken by the taxpayer in its return. ***

By examining the work papers the accountant discharges its own duty to determine "the adequacy and reasonableness of the corporation's reserve account for contingent tax liabilities." United States v. Arthur Young & Co., 465 U.S. 805, 812, 104 S. Ct. 1495, 79 L. Ed. 2d 826 (1983) (rejecting claim of accountant work product privilege protecting such work papers). ***

In Textron's case, its Tax Department lists items in the tax return that, if identified and challenged by the IRS, could result in additional taxes being assessed. The final spreadsheets list each debatable item, including in each instance the dollar amount subject to possible dispute and a percentage estimate of the IRS' chances of success. Multiplying the amount by the percentage fixes the reserve entered on the books for that item. The spreadsheets reflecting these calculations may be supported by backup emails or notes. ***

Textron had shown the spreadsheets to its outside accountant, Ernst & Young, but refused to show them to the IRS. ***

Any experienced litigator would describe the tax accrual work papers as tax documents and not as case preparation materials***

From the outset, the focus of work product protection has been on materials prepared for use in litigation, whether the litigation was underway or merely anticipated. ***

It is not enough to trigger work product protection that the subject matter of a document relates to a subject that might conceivably be litigated. Rather, as the Supreme Court explained, "the literal language of [Rule 26(b)(3)] protects materials prepared for any litigation or trial as long as they were prepared by or for a party to the subsequent litigation." Federal Trade Commission v. Grolier In., 462 U.S. 19, 25, 103 S. Ct. 2209, 76 L. Ed. 2d 387 (1983) (emphasis added). This distinction is well established in the case law. See, e.g., NLRB v. Sears, Roebuck & Co., 421 U.S. 132, 138, 95 S. Ct. 1504, 44 L. Ed. 2d 29 (1975). Nor is it enough that the materials were prepared by lawyers or represent legal thinking. Much corporate material prepared in law offices or reviewed by lawyers falls in that vast category. It is only work done in anticipation of or for trial that is protected. Even if prepared by lawyers and reflecting legal thinking, "[m]aterials assembled in the ordinary course of business, or pursuant to public requirements unrelated to litigation, or for other nonlitigation purposes are not under the qualified immunity provided by this subdivision." ***

Every lawyer who tries cases knows the touch and feel of materials prepared for a current or possible (i.e., "in anticipation of") law suit. They are the very materials catalogued in Hickman v. Taylor and the English precedent with which the decision began. No one with experience of law suits would talk about tax accrual work papers in those terms. A set of tax reserve figures, calculated for purposes of accurately stating a company's financial figures, has in ordinary parlance only that purpose: to support a financial statement and the independent audit of it. ***

The privilege aimed centrally at protecting the litigation process, ... specifically, work done by counsel to help him or her in litigating a case. It is not a privilege designed to help the lawyer prepare corporate documents or other materials prepared in the ordinary course of business. Where the rationale for a rule stops, so ordinarily does the rule.

Nor is there present here the concern that Hickman v. Taylor stressed about discouraging sound preparation for a law suit. That danger may exist in other kinds of cases, but it cannot be present where, as here, there is in substance a legal obligation to prepare such papers: the tax audit work papers not only have a different purpose but have to be prepared by exchange-listed companies to comply with the securities laws and accounting principles for certified financial statements. Arthur Young made this point in refusing to create an accountant's work product privilege for tax audit papers ***.