Since stock option plans are a form of compensation, generally accepted accounting principles, or GAAP, requires businesses to record stock options as a compensation expense for accounting purposes. Rather than recording the expense as the current stock price, the business must calculate the fair market value of the stock option. The accountant will then book accounting entries to record compensation expense, the exercise of stock options and the expiration of stock options.

Initial Value Calculation

Businesses may be tempted to record stock award journal entries at the current stock price. However, stock options are different. GAAP requires employers to calculate the fair value of the stock option and record compensation expense based on this number. Businesses should use a mathematical pricing model designed for valuing stock. The business should also reduce the fair value of the option by estimated forfeitures of stock. For example, if the business estimates that 5 percent of employees will forfeit the stock options before they vest, the business records the option at 95 percent of its value.

Periodic Expense Entries

Instead of recording the compensation expense in one lump sum when the employee exercises the option, accountants should spread the compensation expense evenly over the life of the option. For example, say that an employee receives 200 shares of stock valued by the business at $5,000 that vests in five years. Each year, the accountant debits compensation expense for $1,000 and credits the stock options equity account for $1,000.

Exercise of Options

Accountants need to book a separate journal entry when the employees exercise stock options. First, the accountant must calculate the cash that the business received from the vesting and how much of the stock was exercised. For example, say the employee from the previous example exercised half of his total stock options at an exercise price of $20 a share. Total cash received is $20 multiplied by 100, or $2,000. The accountant debits cash for $2,000; debits a stock options equity account for half of the account balance, or $2,500; and credits the stock equity account for $4,500.

Expired Options

An employee may leave the company before the vesting date and be forced to forfeit her stock options. When this happens, the accountant must make a journal entry to relabel the equity as expired stock options for balance sheet purposes. Although the amount remains as equity, this helps managers and investors understand that they won't be issuing stock to the employee at a discounted price in the future. Say that the employee in the previous example leaves before exercising any of the options. The accountant debits the stock options equity account and credits the expired stock options equity account.