What type of financial statement fraud involves recording transactions in incorrect periods?

The correct answer is timing differences, which refers to the manipulation of the timing of transactions to present a misleading picture of a company's financial performance or position. This type of fraud occurs when financial statement items are recorded in a period other than when they actually occurred, thereby affecting revenue, expenses, and profits reported for that specific period.

By shifting transactions across periods, a company can inflate or deflate its reported earnings to meet financial targets, manipulate stock prices, or comply with loan covenants. This practice can mislead investors and stakeholders about the company's true financial health.

Other options relate to different forms of financial misrepresentation. Improper asset valuations involve overstating or understating the value of assets on the balance sheet, while improper disclosures refer to failing to reveal relevant information that could affect users' understanding of the financial statements. Concealed expenses involve hiding certain costs from financial statements to improve perceived profitability. All of these represent different fraudulent activities, but timing differences particularly focus on the inappropriate allocation of transaction dates, making it the correct choice in this case.