[The following paragraphs of AS 6101, amended to read as follows, will be effective for audits of fiscal years ending on or after December 15, 2017. See PCAOB Release No. 2017-001. The current standard can be found here.]

.27     When the report on the audited financial statements and financial statement schedules included (incorporated by reference) in the registration statement includes one or more explanatory paragraphs or a paragraph to emphasize a matter regarding the financial statements, the accountants should refer¹⁸ to that fact in the comfort letter and discuss the subject matter of the paragraph.¹⁹ In those rare instances in which the SEC accepts a qualified opinion on historical financial statements, the accountants should refer to the qualification in the opening paragraph of the comfort letter and discuss the subject matter of the qualification. (See also paragraph .35f.) 

¹⁸     The accountants may also refer in the opening paragraph to expansions of their report that do not affect their opinion on the basic financial statements, for example, expansions of their report regarding (a) interim financial information accompanying or included in the notes to audited financial statements (see AS 4105.50) or (b) required supplementary information described in paragraphs .08 through .11 of AS 2705, Required Supplementary Information. See paragraph .30 of this section.

¹⁹     The accountants need not refer to or discuss explanatory paragraphs covering consistency of application of accounting principles.

.30     An underwriter may also request that the accountants comment in their comfort letter on (a) unaudited interim financial information required by item 302(a) of Regulation S-K, to which AS 4105 pertains or (b) required supplementary information, to which AS 2705 pertains. AS 4105 and AS 2705 provide that the accountants should expand the auditor's unqualified report on the audited financial statements to refer to such information when the scope of their procedures with regard to the information was restricted or when the information appears not to be presented in conformity with generally accepted accounting principles or, for required supplementary information, applicable guidelines. Such expansions of the auditor's unqualified report in the registration statement would ordinarily be referred to in the opening paragraph of the comfort letter (see also paragraph .35f). Additional comments on such unaudited information are therefore unnecessary. However, if the underwriter requests that the accountants perform procedures with regard to such information in addition to those performed in connection with their review or audit as prescribed by AS 4105 and AS 2705, the accountants may do so and report their findings. 

.35     Comments included in the letter will often concern (a) unaudited condensed interim financial information (see paragraphs .36 through .38),²⁷ (b) capsule financial information (see paragraphs .36 and .39 through .41), (c) pro forma financial information (see paragraphs .42 and .43), (d) financial forecasts (see paragraphs .36 and .44), and (e) changes in capital stock, increases in long-term debt, and decreases in other specified financial statement items (see paragraphs .36 and .45 through .53). For commenting on these matters, the following guidance is important:

1. As explained in paragraph .16, the agreed-upon procedures performed by the accountants should be set forth in the letter, except that when the accountants have been requested to provide negative assurance on interim financial information or capsule financial information, the procedures involved in an AS 4105 review need not be specified (see paragraphs .37 through .41 of this section and paragraph 4 of example A [paragraph .64]).
2. To avoid any misunderstanding about the responsibility for the sufficiency of the agreed-upon procedures for the underwriter's purposes, the accountants should not make any statements, or imply that they have applied procedures that they have determined to be necessary or sufficient for the underwriter's purposes. If the accountants state that they have performed an AS 4105 review, this does not imply that those procedures are sufficient for the underwriter's purposes. The underwriter may ask the accountants to perform additional procedures. For example, if the underwriter requests the accountants to apply additional procedures and specifies items of financial information to be reviewed and the materiality level for changes in those items that would necessitate further inquiry by the accountants, the accountants may perform those procedures and should describe them in their letter. Descriptions of procedures in the comfort letter should include descriptions of the criteria specified by the underwriter.
3. Terms of uncertain meaning (such as general review, limited review, reconcile, check, or test) should not be used in describing the work, unless the procedures comprehended by these terms are described in the comfort letter.
4. The procedures performed with respect to interim periods may not disclose changes in capital stock, increases in long-term debt or decreases in the specified financial statement items, inconsistencies in the application of generally accepted accounting principles, instances of noncompliance as to form with accounting requirements of the SEC, or other matters about which negative assurance is requested. An appropriate manner of making this clear is shown in the last three sentences in paragraph 4 of example A [paragraph .64].
5. Matters to be covered by the letter should be made clear in the meetings with the underwriter and should be identified in the underwriting agreement and in the draft comfort letter. Since there is no way of anticipating other matters that would be of interest to an underwriter, accountants should not make a general statement in a comfort letter that, as a result of carrying out the specified procedures, nothing else has come to their attention that would be of interest to the underwriter.
6. When the report on the audited financial statements and financial statement schedules in the registration statement departs from the auditor's unqualified report, and the comfort letter includes negative assurance with respect to subsequent unaudited condensed interim financial information included (incorporated by reference) in the registration statement or with respect to an absence of specified subsequent changes, increases, or decreases, the accountant should consider the effect thereon of the subject matter of the qualification, explanatory paragraph(s), or paragraph(s) emphasizing a matter regarding the financial statements. The accountant should also follow the guidance in paragraph .27. An illustration of how this type of situation may be dealt with is shown in example I [paragraph .64].

²⁷     The SEC requirements specify condensed financial statements. However, the guidance in paragraphs .37 and .38 also applies to complete financial statements. For purposes of this section, interim financial statements may be for a twelve-month period ending on a date other than the entity's normal year end.

[Effective pursuant to SEC Release No. 34-81916, File No. PCAOB-2017-01 (October 23, 2017)]