One disadvantage of direct taxes is that they

Direct taxes are taxes levied directly on the income or wealth of individuals and organizations. Examples include personal income tax, company income tax, capital gains tax, and property tax. While direct taxes have several advantages (such as being equitable and certain), they also have notable disadvantages.

One key disadvantage is that direct taxes can be evaded. Tax evasion occurs when taxpayers deliberately underreport their income, overstate their deductions, hide assets, or fail to file tax returns in order to reduce or eliminate their tax liability. This is possible because direct taxes rely on taxpayers' honest declaration of their earnings, and enforcement agencies cannot always verify every individual's true income.

Self-employed individuals and business owners, in particular, may find it easier to evade direct taxes by keeping transactions off the books or operating in the informal economy.

The other options do not describe disadvantages of direct taxes:

• Being progressive (where higher earners pay a larger percentage) is generally considered an advantage, as it promotes equity.
• "Not being rigid" is not a recognized disadvantage of direct taxes.
• Allocating scarce resources is a function of the price mechanism, not a characteristic of direct taxes.