delivered the Opinion of the Court.
In
In re Marriage of Miller,
I
The parties were married on June 10, 1983. On November 17, 1988, November 16, 1990, and November 21, 1991, the husband received nonstatutory stock options from his employer, Hewlett-Packard Company (HP), pursuant to a corporate incentive compensation plan. Each option is subject to the terms and conditions set forth in a stock option agreement. Each agreement provides that on the first, second, third, and fourth anniversaries of the agreement the option is exercisable as to one-quarter, one-half, three-quarters, and all of the option stock, respectively. Each agreement further provides that all rights to exercise the option will terminate upon the termination of the husband’s employment “for any reason other than retirement because of age or permanent and total disability,” or after ten years, whichever occurs first. Each agreement also describes circumstances in which the death of the employee might result in the termination of the option. William Brunelli, a personnel manager of HP, testified that these stock options are commonly granted each year to the company’s high level and top performing employees.
On July 17, 1991, HP granted the husband 2,500 shares of restricted stock. The restricted stock agreement provides that the stock shares will vest and the restriction period will expire five years from the date of the agreement and that during the restriction period the husband cannot transfer or pledge his interest in the stock shares, but retains all other rights associated with ownership of the stock shares, including the rights to vote the stock and to receive cash dividends. The agreement also contains provisions affecting the husband’s right to retain all or portions of the restricted stock shares in the event of the termination of the husband’s employment prior to the expiration of the restriction period, the husband’s retirement, the husband’s total and permanent disability, or the husband’s death. Brunelli tes- *1316 tilled that HP rarely grants restricted stock shares to its employees and that such grants are usually awarded as bonuses for completion of some project and as incentives to employees to remain with the company.
The decree of dissolution in this case was entered on November 16, 1992. After conducting a hearing, the trial court entered its permanent orders on May 14, 1993. The trial court found that the stock options had been granted to the husband for services and as an incentive to remain an employee and that the restricted stock shares had been granted to him as a bonus for his activities in closing down a division of HP and as an incentive to encourage the husband to remain an HP employee. Upon these findings and in reliance on
In re Marriage of Frederick,
218 IU.App.3d 533, 161 IU.Dec. 254,
II
The wife argues that aU of the options and aU of the restricted stock shares constitute marital property. Alternatively, she asserts that the marital fraction adopted by the trial court is erroneous. We conclude that the trial court properly determined that only portions of the stock options constitute marital property. However, we further conclude that the formula adopted by the trial court in determining the marital fraction of those options is inappropriate under the circumstances of this case. . We agree with the wife’s argument that all of the restricted stock shares constitute marital property.
A
In a dissolution proceeding, a trial court is required to “divide the marital property” between spouses. § 14-10-113(1), 6B C.R.S. (1987). Marital property is defined as “all property acquired by either spouse subsequent to the marriage” and prior to a decree of legal separation. § 14-10-113(2)(c), 6B C.R.S. (1987). 2 The General Assembly has not defined the meaning of the term “property” for purposes of the Uniform Dissolution of Marriage Act, §§ 14-10-101 to -133, 6B C.R.S. (1987 & 1995 Supp.) (the Act). Furthermore, the General Assembly did not indicate at what point property is acquired for purposes of the Act.
While this court has not previously considered whether or to what extent stock options and restricted stock shares constitute marital property for purposes of the Act, we have addressed similar issues with respect to retirement plans. In
In re Marriage of Grubb,
In
In re Marriage of Gallo,
B
An employee stock option is a contractual right to purchase stock during a specified period at a predetermined price. 2A Research Institute of America, Benefits Coordinator ¶ 31,101 (1995) (2A Benefits Coordinator). While there is no requirement that the option period be limited to a certain duration for nonstatutory stock options, the option period is typically ten years. Id. ¶ 31,154. In addition, while nonstatutory employee stock options may be immediately exercisable upon being granted, for tax planning purposes of both the employer and the employee such options more typically are exercisable only after a waiting period or in incremental portions. Id. ¶ 31,157.
An optionee’s right to exercise an employer-granted stock option is typically related in some manner to the optionee’s employment status. Neal A Mancoff & David M. Weiner, Nonqualified Deferred Compensation Arrangements § 4:47 (1991). By relating an optionee’s rights to exercise stock options to the optionee’s employment status, an employer is able to use stock options as an incentive to employees to continue employment with the employer. An employer may provide for more liberal exercise conditions if the termination of employment occurs by reason of retirement, death, or disability, and may provide for more restrictive exercise conditions if the termination of employment is for “cause” or for other circumstances deemed not to be in the interest of the company. Id. The husband’s stock options in this ease are typical of nonstatutory stock options in that the option period is ten years; the options become exercisable in incremental portions; and, with certain exceptions, the optionee’s abilities to exercise the options lapse upon the termination of employment.
Because the options are not immediately exercisable and the husband may be required to forfeit the options before the options become exercisable, the parties describe the options as nonvested. Characterizing the options as nonvested, though perhaps accurate for purposes of employee benefits and tax law, may be misleading for purposes of ascertaining what interests are marital property for purposes of the Act.
3
For instance, under the Internal Revenue Code, the optionee of a nonstatutory employee stock option must recognize income at the time the option is granted if the
*1318
option has a “readily ascertainable value” at the time of the grant. Treas.Reg. § 1.83-7 (1978);
see
2A Benefits Coordinator ¶31,-146. If the option does not have a readily ascertainable value at the time of the grant, the optionee recognizes income at the time the option becomes “substantially vested” or no longer subject to a “substantial risk of forfeiture,” which generally does not oceur until the option is exercised.
See
I.R.C. § 83(a) (1994); Treas.Reg. § 1.83-1, -7 (1978);
see also
2A Benefits Coordinator ¶ 31,146. For purposes of determining the marital nature of an employee’s right to receive certain benefits in the future, however, vesting occurs when the employee has completed the minimum terms of employment necessary for the employee to be entitled to receive the benefits, whether or not the benefit has a readily ascertainable value or is subject to a substantial risk of forfeiture.
Grubb,
A nonvested interest is an expectancy and not property because the holder has no enforceable rights.
See In re Marriage of Jones,
The trial court found in this case that the options were granted in consideration of services and as an incentive for continued employment with the company. Unlike pension benefits, employee stock options may well be considered compensation for future services as well as for past and for present services.
In re Marriage of Hug,
*1319
In view of these considerations, we conclude that to the extent an employee stock option is granted in consideration of past services, the option may constitute marital property when granted.
8
See Grubb,
The trial court and the court of appeals in essence recognized this distinction in holding that the wife was entitled only to portions of the husband’s stock options. However, the trial court’s time-rule formula and resulting formulation of the applicable marital fraction assume that the options were granted solely for future services, in that the formula treats the options as marital property only to the extent that future services were rendered prior to the entry of the decree of dissolution. The formula adopted by the trial court thus fails to acknowledge the fact that some portions of the options may have constituted marital property at the time the options were granted to the husband.
Although the trial court found that the stock options were granted in consideration of services, it did not determine the extent to which each option represented consideration for past or future services. Under this circumstance, the case must be remanded to the trial court with directions to determine, with respect to each option, what portion was granted in consideration of past services and what portion was granted in consideration of future services. 9 Upon making that determination, the trial court should then determine an appropriate means of evaluating those portions of the stock options that reflect compensation for future services. The portions of the stock options granted in consideration of past services may, as we have indicated, constitute marital property in their entirety.
C
The wife argues that the restricted stock shares constitute marital property in their entirety. We agree.
Although language contained in the restricted stock agreement in this case suggests that the agreement is based on consideration of both past and future services by the husband, the agreement’s grant of authority to the husband to exercise ownership rights in those stock shares is inconsistent with that suggestion. In addition, although the restricted stock agreement indicates that the restricted stock shares are subject to forfeiture during the five years after the date of the agreement, HP cannot unilaterally repudiate the husband’s right to retain the stock. The husband received the shares; he was not granted a conditional right to receive the shares. Because the husband had already earned the right to receive those shares, they represent a form of deferred compensation and thus constitute marital
*1320
property for purposes of the Act.
Grubb,
Ill
For the foregoing reasons, we affirm the determination of the trial court and the court of appeals that portions of the husband’s stock options constitute marital property. However, we conclude that the trial court failed to adopt a formula for evaluation of the stock options that adequately recognizes the fact that those portions of such options representing deferred compensation for past services may constitute marital property. We also conclude that the restricted stock shares constitute marital property in their entirety, contrary to the determinations of the court of appeals and the trial court. We therefore affirm in part and reverse in part the judgment of the court of appeals and remand the case to that court with directions to vacate the trial court’s permanent orders and return the case to the trial court for further proceedings consistent with this opinion.
Notes
. The trial court assumed that the 1988 stock option had been exercised and distributed.
. Section 14-10-113(2) contains other exceptions to the general definition of marital property which are not applicable in this case.
. Other courts have recognized the varied use of the term "vested.”
See In re Marriage of Brown,
. A company may retain the right to revoke the option under certain circumstances before the option has been exercised. 2A Benefits Coordinator ¶ 31,159.
. The plan under which these options were granted is called the Hewlett-Packard Company Incentive Compensation Plan. Under the plan, an employee may immediately sell the stock purchased pursuant to the option. By doing so, an employee is able to finance the purchase and the employee realizes as income the difference between the sale price and the option price.
. Options granted in consideration of present services may also be deemed a form of deferred compensation.
See In re Marriage of Short,
. There is a distinction between conditioning the receipt of benefits on the employee remaining in the employ of the employer and providing benefits in consideration of the performance of future
*1319
services.
See Grubb,
. The record before us does not indicate whether any portion of any of the stock options in question was granted in consideration of services rendered by the husband prior to the marriage. We therefore do not consider issues which may arise from such circumstances.
. Whether an employee stock option is characterized as granted in consideration of past or future services depends on the circumstances surrounding the grant and the effect of the option agreement. For example, in
In re Marriage of Hug,
