2019 LTIP. In April 2019, our common unitholders approved the 2019 Long-Term Incentive Plan (2019 LTIP) for eligible employees, consultants and directors of NuStar Energy L.P., and of NuStar GP, LLC, and their respective affiliates who perform services for us and our subsidiaries. The 2019 LTIP allows for the awarding of (i) options; (ii) restricted units; (iii) distribution equivalent rights (DERs); (iv) performance cash; (v) performance units; and (vi) unit awards. DERs entitle the participant to receive cash equal to cash distributions made on any award prior to its vesting. The 2019 LTIP permits the granting of awards totaling an aggregate of 2,500,000 common units, subject to adjustment as provided in the 2019 LTIP. The 2019 LTIP generally will be administered by the compensation committee of our board of directors. As of December 31, 2020, a total of 399,790 common units remained available to be awarded under the 2019 LTIP.

2000 LTIP. We sponsor the 2000 Long-Term Incentive Plan, as amended (2000 LTIP), which terminated with respect to new grants when the unitholders approved the 2019 LTIP. However, unvested restricted unit and performance unit awards granted under the 2000 LTIP remain outstanding.

2006 LTIP. Effective July 20, 2018 and in conjunction with the Merger, we assumed the 2006 Long-Term Incentive Plan, as amended (the 2006 LTIP). Prior to the Merger, Holdings sponsored the 2006 LTIP. At the effective time of the Merger, each outstanding award of Holdings restricted units was converted, on the same terms and conditions as were applicable to the awards immediately prior to the Merger, into an award of NuStar Energy restricted units. The number of NuStar Energy restricted units subject to the converted awards was determined pursuant to the 0.55 exchange ratio provided in the Merger agreement. The Holdings units remaining available to be awarded under the 2006 LTIP were also converted pursuant to the


	Units Outstanding December 31,			Compensation Expense Year Ended December 31,
	2020	2019	2018	2020		2019		2018
				(Thousands of Dollars)
Restricted units:
Domestic employees	2,235,125	1,223,143	1,028,484	$	10,205	$	9,437	$	8,233
Non-employee directors (NEDs)	98,769	61,349	59,752	631		774		524
International employees	19,987	10,243	30,918	58		711		1,158
Performance awards	87,122	161,561	158,326	1,291		4,172		1,889

Unit awards	—	—	—	—		22,941		18,895
Total	2,441,003	1,456,296	1,277,480	$	12,185	$	38,035	$	30,699

Our restricted unit awards are considered phantom units, as they represent the right to receive our common units upon vesting. We account for restricted units as either equity-classified awards or liability-classified awards, depending on expected method of settlement. Awards we settle with the issuance of common units upon vesting are equity-classified. Awards we settle in cash upon vesting are liability-classified. We record compensation expense ratably over the vesting period based on the fair value of the common units at the grant date (for domestic employees and NEDs) or the fair value of the common units measured at each reporting period (for international employees). DERs paid with respect to outstanding equity-classified unvested restricted units reduce equity, similar to cash distributions to unitholders, whereas DERs paid with respect to outstanding liability-classified unvested restricted units are expensed. In connection with the DERs for equity awards, we paid $2.1 million, $2.7 million and $2.0 million respectively, in cash, for the years ended December 31, 2020, 2019 and December 31, 2018.

Non-Employee Directors. The outstanding restricted units granted to NEDs are equity-classified awards that vest over three years. On January 1, 2019 we adopted amended guidance that allows for the fair value of these awards to be measured at the grant date. The unvested restricted units granted to NEDs as of January 1, 2019 were measured at the fair value as of that date. Previously, the fair value of these awards was equal to the market price of our common units at each reporting period.

International Employees. The outstanding restricted units granted to international employees are cash-settled and accounted for as liability-classified awards. These awards vest over three years and the fair value is equal to the market price of our common units at each reporting period. For the year ended December 31, 2020, we granted 14,581 restricted units and 4,837 restricted units vested.


	Measured at Grant Date Fair Value			Measured at Market Price
	Number of Units	Weighted-Average Fair Value Per Unit		Number of NEDs Units
Nonvested units as of January 1, 2018	736,746	$	35.95	27,097
Converted on July 20, 2018	53,447	24.99		18,915
Granted	518,282	24.07		34,303
Vested	(235,746)	35.12		(20,563)
Forfeited	(44,245)	36.05		—
Nonvested units as of December 31, 2018	1,028,484	29.47		59,752
Change in measurement (a)	59,752	20.93		(59,752)
Granted	596,881	26.46		—
Vested	(328,386)	30.11		—
Forfeited	(72,239)	28.05		—
Nonvested units as of December 31, 2019	1,284,492	27.48		—
Granted	1,454,998	12.10		—
Vested	(374,847)	28.47		—
Forfeited	(30,749)	26.75		—
Nonvested units as of December 31, 2020	2,333,894	17.70		—

The total fair value of our equity-classified restricted unit awards vested for the years ended December 31, 2020, 2019 and 2018 was $4.6 million, $9.3 million and $6.2 million, respectively. We issued 275,146, 242,199 and 189,399 common units in connection with these award vestings, net of employee tax withholding requirements, for the years ended December 31, 2020, 2019 and 2018, respectively. Unrecognized compensation cost related to our equity-classified employee awards totaled $38.1 million as of December 31, 2020, which we expect to recognize over a weighted-average period of 3.8 years.

Performance awards are issued to certain of our key employees and represent either rights to receive our common units or cash upon achieving performance measures for the performance period established by the NuStar GP, LLC Compensation Committee. Achievement of the performance measures determines the rate at which the performance awards convert into our common units or cash, which ranges from zero to 200% for certain awards.

Performance awards vest in three annual increments (tranches), based upon our achievement of the performance measures set by the Compensation Committee during the performance periods that end on December 31 of each applicable year. Therefore, the performance awards are not considered granted for accounting purposes until the Compensation Committee has set the performance measures for each tranche of awards. Performance unit awards are equity-classified awards measured at the grant date fair value. In addition, since the performance unit awards granted do not receive DERs, the grant date fair value of these awards is reduced by the per unit distributions expected to be paid to common unitholders during the vesting period. Performance cash awards are accounted for as a liability but may be settled in common units. We record compensation expense ratably for each vesting tranche over its requisite service period (one year) if it is probable that the specified performance measures will be achieved. Additionally, changes in the actual or estimated outcomes that affect the quantity of performance awards expected to be converted into common units or paid in cash, are recognized as a cumulative adjustment. Performance units vested relate to the performance for the performance period ended December 31 of the previous year.


		Granted for Accounting Purposes
	Total Performance Unit Awards	Performance Unit Awards	Weighted-Average Grant Date Fair Value per Unit
Outstanding as of January 1, 2018	80,961	38,865	$	50.04
Granted	116,230	80,690	23.43


Forfeitures	(38,865)	(38,865)	50.04
Outstanding as of December 31, 2018	158,326	80,690	23.43
Granted	95,969	74,439	28.01
Vested	(80,690)	(80,690)	23.43
Forfeitures	(12,044)	—	—
Outstanding as of December 31, 2019	161,561	74,439	28.01
Granted	—	57,448	13.21
Performance adjustment (a)	72,951	72,951	28.01
Vested	(147,390)	(147,390)	28.01

Outstanding as of December 31, 2020	87,122	57,448	13.21

The total fair value of our performance unit awards vested for the years ended December 31, 2020 and 2019 was $4.2 million and $2.1 million, respectively. For the years ended December 31, 2020 and 2019, we issued 93,440 and 50,054 common units in connection with these award vestings, net of employee tax withholding requirements, respectively, that relate to the performance periods ended December 31 of each previous year. For the year ended December 31, 2018, no performance units vested with respect to the performance period ended December 31, 2017.

For the year ended December 31, 2020, performance cash awards of $2.2 million were granted that vest in three annual tranches. On February 1, 2021, we settled the first tranche of the performance cash awards in common units, and together with the performance unit awards, we issued 58,070 common units, net of employee tax withholding requirements.

Unit awards are equity-classified awards of fully vested common units. We accrued compensation expense in 2019 and 2018 that was paid in unit awards in the first quarter of the subsequent year. We base the number of unit awards granted on the fair value of the common units at the grant date. A summary of our unit awards is shown below: