Our 2019 Equity Incentive Plan and as amended and restated (the 2019 Plan), approved in May 2019, provides for the grant of stock awards, including stock options, RSUs, RSAs, and other stock awards. There were approximately 5 million shares available for grant under the 2019 Plan as of December 31, 2023.

The 2009 Equity Incentive Plan (the 2009 Plan), was replaced by the 2019 Plan, except that any outstanding awards granted under the 2009 Plan remain in effect pursuant to their terms.

Stock options are granted to employees at exercise prices equal to the fair market value of our common stock on the dates of grant. Stock options generally have a maximum contractual term of 10 years. Stock options generally vest over 4 years, and are generally forfeited if the employee terminates service prior to vesting.


	Number of Shares	Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (in years)	Aggregate Intrinsic Value (in millions)
Balance at December 31, 2022	190,275	$	20.50	1.5	$	9

Exercised	(182,067)	20.50			14



Balance at December 31, 2023 (1)	8,208	$	19.50	0.45	$	1


	Year Ended December 31,
Additional Disclosures for Stock Options (in millions)	2023	2022	2021


Total intrinsic value of options exercised	14	8	6
Cash received from options exercised	4	1	1

Time-based RSUs generally vest over a four-year term. Performance-based RSUs are subject to vesting requirements and are earned, in part, based on certain financial performance metrics as defined in the grant notice. Actual number of shares earned may range from 0% to 200% of the target award. Performance-based awards granted in 2023, 2022 and 2021 are earned based on a single-year performance period subject to subsequent multi-year time-based vesting with 50% of the shares earned vesting in one year after the performance period and the remaining shares in the year after. RSUs are generally forfeited if the participant terminates service prior to vesting.



	Total Number of RSUs	Weighted-Average Grant Date Fair Value
Nonvested at December 31, 2022	1,198,561	$	80.75
Granted	769,286	78.27
Vested	(617,937)	76.25
Forfeited	(120,708)	82.58
Nonvested at December 31, 2023	1,229,202	$	80.88



	Year Ended December 31,
Additional Disclosures for equity-based plans	2023		2022		2021
Total grant date fair value of shares granted (in millions)	$	60	$	85	$	47
Total grant date fair value of shares vested (in millions)	$	47	$	42	$	34
Shares withheld to settle payroll tax liabilities related to vesting of shares held by employees	213,569		204,191		207,603

Performance-based RSUs



	Total Number Shares	Weighted-Average Grant Date Fair Value
Nonvested at December 31, 2022	202,586	$	86.82
Granted	177,067	79.05
Vested	(156,642)	86.22


Nonvested at December 31, 2023	223,011	$	81.08



	Year Ended December 31,
Additional Disclosures for equity-based plans	2023		2022		2021
Total grant date fair value of shares granted (in millions) (1)	$	14	$	20	$	16
Total grant date fair value of shares vested (in millions)	$	14	$	17	$	8
Shares withheld to settle payroll tax liabilities related to vesting of shares held by employees	74,923		119,901		77,787

Our 2014 Employee Stock Purchase Plan (ESPP) offers eligible employees an option to purchase shares of our common stock through payroll deductions. The purchase price is equal to the lesser of 85% of the fair market value of our common stock on the offering date or 85% of the fair market value of our common stock on the applicable purchase date. Offering periods are approximately six months in duration and will end on or about May 15 and November 15 of each year. The plan is considered to be a compensatory plan. As of December 31, 2023, approximately 5 million shares were reserved for future issuances under the ESPP.


	Year Ended December 31,
(in millions)	2023		2022		2021
Expected Term (in Years)	0.5		0.5		0.5
Expected Volatility	29-35%		21-39%		21-35%
Risk-Free Interest Rate	5.3-5.4%		0.7-4.5%		0.4-0.7%
Expected Dividend Yield	0	%	0	%	0	%

Shares Issued under ESPP	175,446		158,134		136,861

Stock based compensation expense is measured based on the fair value of the stock award on the grant date and recognized over the requisite service period for each separately vesting portion of the stock award. Stock based compensation expense and other disclosures for stock based awards made to our employees pursuant to the equity plans were as follows:


	Year Ended December 31,
(in millions)	2023		2022		2021
Cost of providing services	$	14	$	13	$	12
Sales and marketing	8		7		6
General and administrative	33		38		29
Systems development and programming costs	4		4		3
Total stock based compensation expense	$	59	$	62	$	50
Total stock based compensation capitalized	$	3	$	1	$	1
Income tax benefit related to stock based compensation expense	$	13	$	13	$	10
Tax benefit realized	$	19	$	14	$	16


	Amount (in millions)		Weighted-Average Period (in Years)

Nonvested time based RSUs	$	92	2.47
Nonvested performance based RSUs	10		1.66