世の中には色々嫌な手紙がある。その中で最上位にくるのが税務署からの税務調査通知だ。毎年5月になると税金の季節が終わったという雰囲気が漂うが、実はこの時期が税務署の本格的な始動時期に当たる。一部の納税者にとってはストレスの高まる時期とも言える。これを完全に防ぐ方法は存在しない。特に、無作為抽出では手の施しようがないし、納税者が問題意識を持っていなくても、税務当局が意外な対応をしてくることもある。そうした不確実性による納税者の心配を少しでも和らげる為か、当局は所内の職員ハンドブックとして税務調査の際に実際に使う手順書(IRS Internal Revenue Service Manual )を公開している。どのようなものかを見ておくと、安心に繋がるに相違ない。最も興味を引く箇所は、Part 4 Examination Processであろう。その中に、Minimum Requirements For Examination of Income（必須手順）という箇所があるため、一部を紹介する。税務調査対策として役に立つに違いない。
Testing Gross Receipts (Individual Business Returns)
Test gross business receipts to verify that all the gross receipts are accounted for. For additional techniques, see IRM（Internal Revenue Manual) 18.104.22.168, Testing Gross Receipts or Sales.
1. Trace original entries in the books back to the original sales document (e.g., sales slips, cash register receipts, or job contracts, etc.).
2. Trace original sales documents to the corresponding entries in the books.
3. If original sales documents are numbered or otherwise sequenced, identify and account for missing sales documents.
4. Determine the method and adequacy of the accounting for merchandise withdrawn for personal use.
5. Scan sales agreements, contracts and other related documents to identify unreported bonuses, awards, kickbacks, etc.
6. Determine that all accounts receivables are included in income for accrual basis taxpayers.
Specific Item Method
1. The specific item method involves the use of direct evidence to determine the tax liability based on omitted income, overstated expenses, or both. For example, funds from known sources are tracked to deposits made to a taxpayer’s bank account rather than analyzing bank deposits to identify unreported income from likely sources.
2. Direct evidence is evidence from which only one logical conclusion can be reached. Direct documentary evidence is generally regarded as having the greatest value; and, when possible, examiners should ask to see the original documents when there is reason to believe they exist. Documentary evidence should not be relied upon to the exclusion of facts established through oral testimony or other techniques, such as a tour of the business site.
3. The specific item method is appropriate when the taxpayer maintains books and records, adjustments are due to technical issues (such as timing or character of funds), or the potential sources of unreported income are limited (such as an insurance agent who underwrites for several companies).
4. The specific item method is not useful if the taxpayer’s gross receipts are generated from numerous sources or in small amounts, such as a grocery store.
1. The indirect method involves the use of circumstantial evidence to determine the tax liability based on omitted income, overstated expenses, or both. Circumstantial evidence is evidence from which more than one logical conclusion can be reached. To support adjustments for additional taxable income, both the credibility of the evidence and the reasonableness of the conclusion must be evaluated before the determination of tax liability is made.
2. Analytical reviews and testing of the taxpayer’s books and records, as required by the minimum income probes, may result in the identification of additional taxable income based on circumstantial evidence from which an inference can be made. The financial status analysis and bank account analysis are not prohibited by IRC 7602(e), Limitation on the Use of Financial Status Audit Techniques, simply because an adjustment to taxable income supported by indirect (circumstantial) evidence may be the result.
3. Evaluating Evidence, for complete discussion.
Formal Indirect Method
1. The formal indirect methods are audit techniques used to determine the tax liability based on the amount of unreported income.
1) IRM 22.214.171.124.3, Source and Application of Funds Method
2) IRM 126.96.36.199.4, Bank Deposit and Cash Expenditures Method
3) IRM 188.8.131.52.5, Markup Method
4) IRM 184.108.40.206.6, Unit and Volume Method
5) IRM 220.127.116.11.7, Net Worth Method
2. The formal indirect methods are also known as financial status audit techniques. See IRM 18.104.22.168.1 for additional discussion. They are distinguishable from other audit techniques by the following characteristics:
1) Reliance on indirect evidence of income,
2) In-depth analysis of actual costs that requires the extensive collection of detailed information, and
3) Subject to IRC 7602(e), which states, “the Secretary shall not use financial status or economic reality examination techniques to determine the existence of unreported income of any taxpayer unless the Secretary has a reasonable indication that there is a likelihood of such unreported income.”
3. Formal indirect methods are appropriate when:
1) The taxpayer’s books and records are missing, incomplete, or irregularities are identified; or
2) The financial status analysis indicates a material imbalance of cash flows after consideration of other adjustments identified during the examination.
Minimum Income Probes: Corporations and Other “Business” Returns
1. Balance Sheet: Prepare a Balance Sheet Analysis. See IRM 22.214.171.124.4.1.
2. Reconciliation: Reconcile Schedules M1,M2,and M3.See IRM 126.96.36.199.4.2.
3. Shareholder and Partners
Evaluate the tax returns of significant shareholders or partners. See IRM 188.8.131.52.4.3.
Interview the taxpayer. See IRM 184.108.40.206.4.4.
5. Tour of Business Perform a tour of the business site. See IRM 220.127.116.11.4.5.
6. Internal Controls Evaluate the internal controls. See IRM 18.104.22.168.4.6.
7. Gross Receipts Test
Gross receipts or sales. See IRM 22.214.171.124.4.7.
8. Ratio Analysis: Prepare a business ratio analysis. See IRM 126.96.36.199.4.8.
9. E-Commerce and/or Internet Use
Determine if there are Internet use and E Commerce income activity. See IRM 188.8.131.52.3.9.
更に、問題の多い業界を対象としたATGS(Audit Techniques Guides )も公開されている（https://www.irs.gov/businesses/small-businesses-self-employed/audit-techniques-guides-atgs）。