When are taxpayers not required to substantiate the amount of an expense according to the Tax Code?

The correct answer relates to the stipulations surrounding the use of standard meal rates in travel expenses. According to the Tax Code, when taxpayers utilize the standard meal allowance for meal expenses incurred during travel, they are not required to provide detailed substantiation for these expenses.

The rationale behind this is that the standard meal rate already establishes a predetermined amount that a taxpayer can deduct for travel-related meals. Since this rate is designed to simplify the reporting and deduction process, taxpayers can opt to use it without the burden of keeping receipts or providing detailed documentation that they would typically need to substantiate actual expenses. This helps streamline the reconciliation of meal costs associated with business travel, simplifying compliance for both the taxpayer and the tax authorities.

In contrast, circumstances where other options suggested would not relieve taxpayers from the obligation to substantiate expenses involve different criteria regarding whether expenses are documented or approved in advance, which goes beyond the use of standardized rates to simplify the process.