The rules that control the timing of the recognition of items of revenue and expense for federal income tax purposes -- tax accounting -- have received little attention in the last two decades. Presumably, this is due in some measure to the time value of money being less interesting in the recent low interest rate environment. With so little recent public discussion, many tax lawyers' understanding of tax accounting rests on historical myths that no longer are true. For example, many tax lawyers think that financial accounting's Generally Accepted Accounting Principles (GAAP) are not relevant to tax accounting because GAAP rests on the principle of "conservatism." This has not been true since 2010. Many tax lawyers think that the only example of when GAAP controls tax accounting is under the LIFO conformity requirement. In fact, in many, many important real cases, this is not true. For example, an accrual basis taxpayer's basic accounting for core items of revenue and expense can be controlled by GAAP. This article explores these and other tax accounting myths.