N-Q 1 d531973dnq.htm NUVEEN CALIFORNIA SELECT TAX-FREE INCOME PORTFOLIO

Nuveen California Select Tax-Free Income Portfolio

UNITED STATES SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

FORM N-Q

QUARTERLY SCHEDULE OF PORTFOLIO HOLDINGS OF REGISTERED MANAGEMENT INVESTMENT COMPANY

Investment Company Act file number 811-06623

Nuveen California Select Tax-Free Income Portfolio

(Exact name of registrant as specified in charter)

Nuveen Investments

    333 West Wacker Drive, Chicago, Illinois 60606     

(Address of principal executive offices) (Zip code)

Gifford R. Zimmerman

Vice President and Secretary

    333 West Wacker Drive, Chicago, Illinois 60606     

(Name and address of agent for service)

Registrant’s telephone number, including area code:     312-917-7700    

Date of fiscal year end: March 31

Date of reporting period: December 31, 2017

Form N-Q is to be used by management investment companies, other than small business investment companies registered on Form N-5 (§§ 239.24 and 274.5 of this chapter), to file reports with the Commission, not later than 60 days after the close of the first and third fiscal quarters, pursuant to rule 30b1-5 under the Investment Company Act of 1940 (17 CFR 270.30b1-5). The Commission may use the information provided on Form N-Q in its regulatory, disclosure review, inspection, and policymaking roles.

A registrant is required to disclose the information specified by Form N-Q, and the Commission will make this information public. A registrant is not required to respond to the collection of information contained in Form N-Q unless the Form displays a currently valid Office of Management and Budget (“OMB”) control number. Please direct comments concerning the accuracy of the information collection burden estimate and any suggestions for reducing the burden to the Secretary, Securities and Exchange Commission, 450 Fifth Street, NW, Washington, DC 20549-0609. The OMB has reviewed this collection of information under the clearance requirements of 44 U.S.C. § 3507.

Item 1. Schedule of Investments

NXC

Nuveen California Select Tax-Free Income Portfolio

Portfolio of Investments December 31, 2017 (Unaudited)

Principal Amount (000)		Description (1)		Optional Call Provisions (2)	Ratings (3)	Value
		LONG-TERM INVESTMENTS – 97.8%
		MUNICIPAL BONDS – 97.8%
		Consumer Staples  – 6.3%
$ 1,000		California County Tobacco Securitization Agency, Tobacco Settlement Asset-Backed Bonds, Gold Country Settlement Funding Corporation, Refunding Series 2006, 5.250%, 6/01/46		6/18 at 100.00	CCC	$999,930
50		California County Tobacco Securitization Agency, Tobacco Settlement Asset-Backed Bonds, Sonoma County Tobacco Securitization Corporation, Series 2005, 4.250%, 6/01/21		6/18 at 100.00	BBB+	50,042
1,095		Golden State Tobacco Securitization Corporation, California, Tobacco Settlement Asset-Backed Bonds, Senior Convertible Series 2007A-2, 5.300%, 6/01/37		6/22 at 100.00	B	1,108,917
		Golden State Tobacco Securitization Corporation, California, Tobacco Settlement Asset-Backed Bonds, Series 2007A-1:
775		5.000%, 6/01/33		3/18 at 100.00	B+	775,015
660		5.750%, 6/01/47		6/18 at 100.00	B3	664,554
1,500		Tobacco Securitization Authority of Northern California, Tobacco Settlement Asset-Backed Bonds, Series 2005A-1, 5.500%, 6/01/45		6/18 at 100.00	B-	1,500,015
1,000		Tobacco Securitization Authority of Southern California, Tobacco Settlement Asset-Backed Bonds, San Diego County Tobacco Asset Securitization Corporation, Senior Series 2006A, 5.000%, 6/01/37		6/18 at 100.00	BB+	1,002,290
6,080		Total Consumer Staples				6,100,763
		Education and Civic Organizations – 3.2%
160		California Municipal Finance Authority, Charter School Revenue Bonds, Rocketship Education Multiple Projects, Series 2014A, 7.250%, 6/01/43		6/22 at 102.00	N/R	182,467
60		California School Finance Authority, School Facility Revenue Bonds, Alliance for College-Ready Public Schools Project, Series 2016A, 5.000%, 7/01/46, 144A		7/25 at 100.00	BBB	66,114
385		California School Finance Authority, School Facility Revenue Bonds, Alliance for College-Ready Public Schools Project, Series 2016C, 5.000%, 7/01/46		7/25 at 101.00	BBB	422,249
250		California Statewide Communities Development Authority, School Facility Revenue Bonds, Alliance College-Ready Public Schools, Series 2011A, 7.000%, 7/01/46		7/21 at 100.00	BBB-	277,850
2,000		University of California, General Revenue Bonds, Limited Project Series 2016K, 4.000%, 5/15/46		5/26 at 100.00	AA-	2,133,220
2,855		Total Education and Civic Organizations				3,081,900
		Health Care – 9.1%
1,000		California Health Facilities Financing Authority, California, Revenue Bonds, Sutter Health, Refunding Series 2016B, 5.000%, 11/15/46		11/26 at 100.00	AA-	1,176,800
2,500		California Health Facilities Financing Authority, California, Revenue Bonds, Sutter Health, Series 2016A, 5.000%, 11/15/41		11/25 at 100.00	AA-	2,934,000
115		California Health Facilities Financing Authority, Revenue Bonds, Lucile Salter Packard Children's Hospital, Series 2014A, 5.000%, 8/15/43		8/24 at 100.00	AA-	130,502
125		California Health Facilities Financing Authority, Revenue Bonds, Providence Health & Services, Refunding Series 2014A, 5.000%, 10/01/38		10/24 at 100.00	AA-	146,175

Principal Amount (000)		Description (1)		Optional Call Provisions (2)	Ratings (3)	Value
		Health Care (continued)
$ 255		California Health Facilities Financing Authority, Revenue Bonds, Providence Health & Services, Series 2014B, 5.000%, 10/01/44		10/24 at 100.00	AA-	$288,800
1,000		California Health Facilities Financing Authority, Revenue Bonds, Providence Saint Joseph Health, Refunding Series 2016A, 4.000%, 10/01/47		10/26 at 100.00	AA-	1,061,350
235		California Health Facilities Financing Authority, Revenue Bonds, Rady Children's Hospital - San Diego, Series 2011, 5.250%, 8/15/41		8/21 at 100.00	AA	257,452
35		California Municipal Finance Authority, Revenue Bonds, Eisenhower Medical Center, Series 2017A, 5.000%, 7/01/42		7/27 at 100.00	Baa2	40,340
130		California Municipal Finance Authority, Revenue Bonds, NorthBay Healthcare Group, Series 2017A, 5.250%, 11/01/41		11/26 at 100.00	BBB-	149,162
350		California Statewide Communities Development Authority, California, Revenue Bonds, Loma Linda University Medical Center, Series 2014A, 5.250%, 12/01/34		12/24 at 100.00	BB+	389,799
		California Statewide Communities Development Authority, California, Revenue Bonds, Loma Linda University Medical Center, Series 2016A:
825		5.000%, 12/01/46, 144A		6/26 at 100.00	BB+	903,136
540		5.250%, 12/01/56, 144A		6/26 at 100.00	BB+	599,594
670		San Buenaventura, California, Revenue Bonds, Community Memorial Health System, Series 2011, 7.500%, 12/01/41		12/21 at 100.00	BB+	767,130
7,780		Total Health Care				8,844,240
		Housing/Multifamily – 0.5%
395		California Municipal Finance Authority, Mobile Home Park Revenue Bonds, Caritas Projects Series 2012A, 5.500%, 8/15/47		8/22 at 100.00	BBB	434,058
		California Municipal Finance Authority, Mobile Home Park Senior Revenue Bonds, Caritas Affordable Housing, Inc. Projects, Series 2014A:
25		5.250%, 8/15/39		8/24 at 100.00	BBB+	27,700
65		5.250%, 8/15/49		8/24 at 100.00	BBB+	71,534
485		Total Housing/Multifamily				533,292
		Tax Obligation/General – 24.0%
1,000		California State, General Obligation Bonds, Various Purpose Refunding Series 2015, 5.000%, 8/01/34		8/25 at 100.00	AA-	1,190,590
1,650		California State, General Obligation Bonds, Various Purpose Series 2009, 5.500%, 11/01/39		11/19 at 100.00	AA-	1,760,781
1,965		California State, General Obligation Bonds, Various Purpose Series 2011, 5.000%, 10/01/41		10/21 at 100.00	AA-	2,186,377
2,000		California State, General Obligation Bonds, Various Purpose Series 2012, 5.250%, 4/01/35		4/22 at 100.00	AA-	2,271,920
2,345		Golden West Schools Financing Authority, California, General Obligation Revenue Refunding Bonds, School District Program, Series 1999A, 0.000%, 2/01/18  –  NPFG Insured		No Opt. Call	A3	2,342,421
1,080		Mountain View-Los Altos Union High School District, Santa Clara County, California, General Obligation Bonds, Capital Appreciation Series 1997C, 0.000%, 5/01/18  –  NPFG Insured		No Opt. Call	Aaa	1,075,280
7,575		Palomar Pomerado Health, California, General Obligation Bonds, Convertible Capital Appreciation, Election 2004 Series 2010A, 0.000%, 8/01/34		No Opt. Call	A	4,165,568
1,000		San Benito High School District, San Benito and Santa Clara Counties, California, General Obligation Bonds, 2016 Election Series 2017, 5.250%, 8/01/46		8/27 at 100.00	Aa3	1,231,010

Principal Amount (000)		Description (1)		Optional Call Provisions (2)	Ratings (3)	Value
		Tax Obligation/General (continued)
$ 8,075		San Bernardino Community College District, California, General Obligation Bonds, Election of 2008 Series 2009B, 0.000%, 8/01/44		No Opt. Call	AA	$2,936,151
1,000		San Francisco Bay Area Rapid Transit District, California, General Obligation Bonds, Election of 2016, Green Series 2017A-1, 5.000%, 8/01/47		8/27 at 100.00	AAA	1,208,900
1,000		Santa Barbara Unified School District, Santa Barbara County, California, General Obligation Bonds, Election of 2016 Series 2017A, 4.000%, 8/01/41		8/27 at 100.00	Aa2	1,094,020
2,000		West Hills Community College District, California, General Obligation Bonds, School Facilities Improvement District 3, 2008 Election Series 2011, 0.000%, 8/01/38  –  AGM Insured (4)		8/31 at 100.00	AA	1,887,380
30,690		Total Tax Obligation/General				23,350,398
		Tax Obligation/Limited – 19.0%
1,000		Bell Community Redevelopment Agency, California, Tax Allocation Bonds, Bell Project Area, Series 2003, 5.625%, 10/01/33  –  RAAI Insured		4/18 at 100.00	AA	1,001,860
2,000		California State Public Works Board, Lease Revenue Bonds, Department of Corrections & Rehabilitation, Various Correctional Facilities Series 2013F, 5.250%, 9/01/33		9/23 at 100.00	A+	2,319,500
360		Chino Redevelopment Agency, California, Merged Chino Redevelopment Project Area Tax Allocation Bonds, Series 2006, 5.000%, 9/01/38  –  AMBAC Insured		3/18 at 100.00	A	360,220
270		Fontana Redevelopment Agency, San Bernardino County, California, Tax Allocation Bonds, Jurupa Hills Redevelopment Project, Refunding Series 1997A, 5.500%, 10/01/27		4/18 at 100.00	A	272,603
3,000		Golden State Tobacco Securitization Corporation, California, Enhanced Tobacco Settlement Asset-Backed Revenue Bonds, Refunding Series 2015A, 5.000%, 6/01/40		6/25 at 100.00	A+	3,464,940
1,215		Los Angeles Community Redevelopment Agency, California, Lease Revenue Bonds, Vermont Manchester Social Services Project, Series 2005, 5.000%, 9/01/37  –  AMBAC Insured		3/18 at 100.00	Aa2	1,217,855
1,000		Los Angeles County Metropolitan Transportation Authority, California, Measure R Sales Tax Revenue Bonds, Senior Series 2016A, 5.000%, 6/01/38		6/26 at 100.00	AAA	1,203,700
3,000		Los Angeles County Metropolitan Transportation Authority, California, Proposition A First Tier Senior Sales Tax Revenue Bonds, Green Series 2017A, 5.000%, 7/01/41		7/27 at 100.00	AAA	3,653,040
1,000		Norco Redevelopment Agency, California, Tax Allocation Bonds, Project Area 1, Series 2009, 7.000%, 3/01/34		3/18 at 100.00	A+	1,009,130
50		Novato Redevelopment Agency, California, Tax Allocation Bonds, Hamilton Field Redevelopment Project, Series 2011, 6.750%, 9/01/40		9/21 at 100.00	BBB+	57,426
60		Patterson Public Finance Authority, California, Revenue Bonds, Community Facilities District 2001-1, Subordinate Lien Series 2013B, 5.875%, 9/01/39		9/23 at 100.00	N/R	67,883
		Patterson Public Financing Authority, California, Revenue Bonds, Community Facilities District 2001-1, Senior Series 2013A:
350		5.250%, 9/01/30		9/23 at 100.00	N/R	392,059
320		5.750%, 9/01/39		9/23 at 100.00	N/R	359,990
30		Riverside County Redevelopment Agency, California, Tax Allocation Bonds, Jurupa Valley Project Area, Series 2011B, 6.500%, 10/01/25		10/21 at 100.00	A	34,964
325		Sacramento City Financing Authority, California, Lease Revenue Refunding Bonds, Series 1993A, 5.400%, 11/01/20  –  NPFG Insured		No Opt. Call	A+	345,725
20		San Clemente, California, Special Tax Revenue Bonds, Community Facilities District 2006-1 Marblehead Coastal, Series 2015, 5.000%, 9/01/40		9/25 at 100.00	N/R	22,113
1,365		San Diego County Regional Transportation Commission, California, Sales Tax Revenue Bonds, Refunding Series 2012A, 5.000%, 4/01/42		4/22 at 100.00	AAA	1,527,258

Principal Amount (000)		Description (1)		Optional Call Provisions (2)	Ratings (3)	Value
		Tax Obligation/Limited (continued)
$ 65		San Francisco City and County Redevelopment Agency Successor Agency, California, Special Tax Bonds, Community Facilities District 7, Hunters Point Shipyard Phase One Improvements, Refunding Series 2014, 5.000%, 8/01/39		8/24 at 100.00	N/R	$71,930
40		Signal Hill Redevelopment Agency, California, Project 1 Tax Allocation Bonds, Series 2011, 7.000%, 10/01/26		4/21 at 100.00	N/R	45,843
1,000		Virgin Islands Public Finance Authority, Matching Fund Loan Notes Revenue Bonds, Series 2012A, 5.000%, 10/01/32  –  AGM Insured		10/22 at 100.00	AA	1,059,890
16,470		Total Tax Obligation/Limited				18,487,929
		Transportation – 6.7%
530		Foothill/Eastern Transportation Corridor Agency, California, Toll Road Revenue Bonds, Refunding Junior Lien Series 2013C, 6.500%, 1/15/43		1/24 at 100.00	Baa3	634,580
		Foothill/Eastern Transportation Corridor Agency, California, Toll Road Revenue Bonds, Refunding Series 2013A:
1,000		5.000%, 1/15/42  –  AGM Insured		1/24 at 100.00	AA	1,124,290
1,170		5.750%, 1/15/46		1/24 at 100.00	BBB-	1,359,657
1,175		6.000%, 1/15/53		1/24 at 100.00	BBB-	1,383,092
800		Long Beach, California, Harbor Revenue Bonds, Series 2015D, 5.000%, 5/15/42		5/25 at 100.00	AA	936,128
955		Port of Oakland, California, Revenue Bonds, Refunding Series 2012P, 5.000%, 5/01/31 (Alternative Minimum Tax)		5/22 at 100.00	A+	1,060,193
5,630		Total Transportation				6,497,940
		U.S. Guaranteed – 10.6% (5)
		California Educational Facilities Authority, Revenue Bonds, Santa Clara University, Series 2008A:
195		5.625%, 4/01/37 (Pre-refunded 4/01/18)		4/18 at 100.00	Aa3 (5)	197,042
2,805		5.625%, 4/01/37 (Pre-refunded 4/01/18)		4/18 at 100.00	N/R (5)	2,833,667
355		California Municipal Finance Authority, Mobile Home Park Revenue Bonds, Caritas Projects Series 2010A, 6.400%, 8/15/45 (Pre-refunded 8/15/20)		8/20 at 100.00	BBB (5)	392,026
1,500		California State Public Works Board, Lease Revenue Bonds, Various Capital Projects, Series 2009-I, 6.375%, 11/01/34 (Pre-refunded 11/01/19)		11/19 at 100.00	Aaa	1,627,905
1,000		Imperial Irrigation District, California, Electric System Revenue Bonds, Refunding Series 2011A, 5.500%, 11/01/41 (Pre-refunded 11/01/20)		11/20 at 100.00	AA- (5)	1,109,140
		Irvine Unified School District Financing Authority, Orange County, California, Special Tax Bonds, Group II, Series 2006A:
35		5.000%, 9/01/26 (Pre-refunded 9/01/18)		9/18 at 100.00	N/R (5)	35,823
80		5.125%, 9/01/36 (Pre-refunded 9/01/18)		9/18 at 100.00	N/R (5)	81,947
135		National City Community Development Commission, California, Tax Allocation Bonds, National City Redevelopment Project, Series 2011, 6.500%, 8/01/24 (Pre-refunded 8/01/21)		8/21 at 100.00	A (5)	157,672
500		Palomar Pomerado Health Care District, California, Certificates of Participation, Series 2009, 6.625%, 11/01/29 (Pre-refunded 11/01/19)		11/19 at 100.00	N/R (5)	545,825
1,100		Palomar Pomerado Health Care District, California, Certificates of Participation, Series 2010, 6.000%, 11/01/41 (Pre-refunded 11/01/20)		11/20 at 100.00	BBB- (5)	1,188,781
415		Pittsburg Redevelopment Agency, California, Tax Allocation Bonds, Los Medanos Community Development Project, Refunding Series 2008A, 6.500%, 9/01/28 (Pre-refunded 9/01/18)		9/18 at 100.00	N/R (5)	428,840

Principal Amount (000)		Description (1)		Optional Call Provisions (2)	Ratings (3)	Value
		U.S. Guaranteed (5) (continued)
$ 160		Rancho Santa Fe CSD Financing Authority, California, Revenue Bonds, Superior Lien Series 2011A, 5.750%, 9/01/30 (Pre-refunded 9/01/21)		9/21 at 100.00	A- (5)	$183,147
25		San Francisco Redevelopment Finance Authority, California, Tax Allocation Revenue Bonds, Mission Bay North Redevelopment Project, Series 2011C, 6.750%, 8/01/41 (Pre-refunded 2/01/21)		2/21 at 100.00	A- (5)	28,884
		San Francisco Redevelopment Financing Authority, California, Tax Allocation Revenue Bonds, Mission Bay South Redevelopment Project, Series 2011D:
25		7.000%, 8/01/33 (Pre-refunded 2/01/21)		2/21 at 100.00	BBB+ (5)	29,071
30		7.000%, 8/01/41 (Pre-refunded 2/01/21)		2/21 at 100.00	BBB+ (5)	34,885
360		Turlock Public Financing Authority, California, Tax Allocation Revenue Bonds, Series 2011, 7.500%, 9/01/39 (Pre-refunded 3/01/21)		3/21 at 100.00	A- (5)	425,085
800		Upland, California, Certificates of Participation, San Antonio Community Hospital, Series 2011, 6.500%, 1/01/41 (Pre-refunded 1/01/21)		1/21 at 100.00	BBB+ (5)	912,656
70		Yorba Linda Redevelopment Agency, Orange County, California, Tax Allocation Revenue Bonds, Yorba Linda Redevelopment Project, Subordinate Lien Series 2011A, 6.500%, 9/01/32 (Pre-refunded 9/01/21)		9/21 at 100.00	A- (5)	81,984
9,590		Total U.S. Guaranteed				10,294,380
		Utilities – 3.3%
645		Long Beach Bond Finance Authority, California, Natural Gas Purchase Revenue Bonds, Series 2007A, 5.500%, 11/15/37		No Opt. Call	A	849,433
2,000		Los Angeles Department of Water and Power, California, Power System Revenue Bonds, Series 2017C, 5.000%, 7/01/42		7/27 at 100.00	Aa2	2,420,260
2,645		Total Utilities				3,269,693
		Water and Sewer – 15.1%
1,000		Bay Area Water Supply and Conservation Agency, California, Revenue Bonds, Capital Cost Recovery Prepayment Program, Series 2013A, 5.000%, 10/01/34		4/23 at 100.00	AA-	1,150,240
1,480		California Infrastructure and Economic Development Bank, Clean Water State Revolving Fund Revenue Bonds, Green Series 2017, 5.000%, 10/01/33		4/27 at 100.00	AAA	1,813,784
		California Pollution Control Financing Authority, Water Furnishing Revenue Bonds, Poseidon Resources Channelside LP Desalination Project, Series 2012:
375		5.000%, 7/01/37 (Alternative Minimum Tax), 144A		7/22 at 100.00	Baa3	408,788
1,160		5.000%, 11/21/45 (Alternative Minimum Tax), 144A		7/22 at 100.00	Baa3	1,259,412
2,000		Escondido Joint Powers Financing Authority, California, Revenue Bonds, Water System Financing, Series 2012, 5.000%, 9/01/41		3/22 at 100.00	AA-	2,219,780
2,000		Irvine Ranch Water District, California, Certificates of Participation, Irvine Ranch Water District Series 2016, 5.000%, 3/01/41		9/26 at 100.00	AAA	2,394,040
1,970		Los Angeles Department of Water and Power, California, Waterworks Revenue Bonds, Series 2014A, 5.000%, 7/01/44		7/24 at 100.00	AA+	2,272,474
1,000		Los Angeles Department of Water and Power, California, Waterworks Revenue Bonds, Series 2017A, 5.000%, 7/01/41		1/27 at 100.00	AA+	1,201,150
620		Los Angeles, California, Wastewater System Revenue Bonds, Green Subordinate Lien Series 2017A, 5.250%, 6/01/47		6/27 at 100.00	AA	760,430
1,000		Santa Clara Valley Water District, California, Water System Revenue Bonds, Refunding Series 2016A, 5.000%, 6/01/31		12/25 at 100.00	Aa1	1,200,660
12,605		Total Water and Sewer				14,680,758
$ 94,830		Total Long-Term Investments (cost $86,035,260)				95,141,293

Principal Amount (000)		Description (1)		Optional Call Provisions (2)	Ratings (3)	Value
		SHORT-TERM INVESTMENTS – 1.0%
		MUNICIPAL BONDS – 1.0%
		Health Care – 1.0%
$ 1,000		California Health Facilities Financing Authority, Revenue Bonds, Childrens Hospital of Orange County, Variable Rate Demand Obligation Series 2009C, 1.540%, 11/01/38 (6)		1/18 at 100.00	A-1+	$ 1,000,000
$ 1,000		Total Short-Term Investments (cost $1,000,000)				1,000,000
		Total Investments (cost $87,035,260) – 98.8%				96,141,293
		Other Assets Less Liabilities – 1.2%				1,180,104
		Net Assets – 100%				$ 97,321,397

Fair Value Measurements

Fair value is defined as the price that would be received upon selling an investment or transferring a liability in an orderly transaction to an independent buyer in the principal or most advantageous market for the investment. A three-tier hierarchy is used to maximize the use of observable market data and minimize the use of unobservable inputs and to establish classification of fair value measurements for disclosure purposes. Observable inputs reflect the assumptions market participants would use in pricing the asset or liability. Observable inputs are based on market data obtained from sources independent of the reporting entity. Unobservable inputs reflect the reporting entity’s own assumptions about the assumptions market participants would use in pricing the asset or liability. Unobservable inputs are based on the best information available in the circumstances. The following is a summary of the three-tiered hierarchy of valuation input levels.

Level 1  –   Inputs are unadjusted and prices are determined using quoted prices in active markets for identical securities.

Level 2  –   Prices are determined using other significant observable inputs (including quoted prices for similar securities, interest rates, prepayment speeds, credit risk, etc.).

Level 3  –   Prices are determined using significant unobservable inputs (including management’s assumptions in determining the fair value of investments).

The inputs or methodologies used for valuing securities are not an indication of the risks associated with investing in those securities. The following is a summary of the Fund’s fair value measurements as of the end of the reporting period:

	Level 1	Level 2	Level 3	Total
Long-Term Investments:
Municipal Bonds	$ —	$95,141,293	$ —	$95,141,293
Short-Term Investments:
Municipal Bonds	—	1,000,000	—	1,000,000
Total	$ —	$96,141,293	$ —	$96,141,293

Income Tax Information

The following information is presented on an income tax basis. Differences between amounts for financial statement and federal income tax purposes are primarily due to timing differences in recognizing taxable market discount, timing differences in recognizing certain gains and losses on investment transactions and the treatment of investments in inverse floating rate securities reflected as financing transactions, if any. To the extent that differences arise that are permanent in nature, such amounts are reclassified within the capital accounts on the Statement of Assets and Liabilities presented in the annual report, based on their federal tax basis treatment; temporary differences do not require reclassification. Temporary and permanent differences do not impact the net asset value of the Fund.

The below table below presents the cost and unrealized appreciation (depreciation) of the Fund's investment portfolio, as determined on a federal income tax basis, as of December 31, 2017.

Tax cost of investments	$86,993,843
Gross unrealized:
Appreciation	$ 9,157,211
Depreciation	(9,761)
Net unrealized appreciation (depreciation) of investments	$ 9,147,450

(1)	All percentages shown in the Portfolio of Investments are based on net assets.
(2)	Optional Call Provisions: Dates (month and year) and prices of the earliest optional call or redemption. There may be other call provisions at varying prices at later dates. Certain mortgage-backed securities may be subject to periodic principal paydowns.
(3)	For financial reporting purposes, the ratings disclosed are the highest of Standard & Poor’s Group (“Standard & Poor’s”), Moody’s Investors Service, Inc. (“Moody’s”) or Fitch, Inc. (“Fitch”) rating. This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Ratings below BBB by Standard & Poor’s, Baa by Moody’s or BBB by Fitch are considered to be below investment grade. Holdings designated N/R are not rated by any of these national rating agencies.
(4)	Step-up coupon bond, a bond with a coupon that increases ("steps up"), usually at regular intervals, while the bond is outstanding. The rate shown is the coupon as of the end of the reporting period.
(5)	Backed by an escrow or trust containing sufficient U.S. Government or U.S. Government agency securities, which ensure the timely payment of principal and interest.
(6)	Investment has maturity of greater than one year, but has variable rate and/or demand features which qualify it as a short-term investment. The rate disclosed, as well as the reference rate and spread, where applicable, is that in effect as of the end of the reporting period. This rate changes periodically based on market conditions or a specified market index.
144A	Investment is exempt from registration under Rule 144A of the Securities Act of 1933, as amended. These investments may only be resold in transactions exempt from registration, which are normally those transactions with qualified institutional buyers.

Item 2. Controls and Procedures.

a. The registrant’s principal executive and principal financial officers, or persons performing similar functions, have concluded that the registrant’s disclosure controls and procedures (as defined in Rule 30a-3(c) under the Investment Company Act of 1940, as amended (the “1940 Act”) (17 CFR 270.30a-3(c))) are effective, as of a date within 90 days of the filing date of this report that includes the disclosure required by this paragraph, based on their evaluation of the controls and procedures required by Rule 30a-3(b) under the 1940 Act (17 CFR 270.30a-3(b)) and Rule 13a-15(b) or 15d-15(b) under the Securities Exchange Act of 1934 (17 CFR 240.13a-15(b) or 240.15d-15(b)).

b. There were no changes in the registrant’s internal control over financial reporting (as defined in Rule 30a-3(d) under the 1940 Act (17 CFR 270.30a-3(d)) that occurred during the registrant’s last fiscal quarter that have materially affected, or are reasonably likely to materially affect, the registrant’s internal control over financial reporting.

Item 3. Exhibits.

File as exhibits as part of this Form a separate certification for each principal executive officer and principal financial officer of the registrant as required by Rule 30a-2(a) under the 1940 Act (17 CFR 270.30a-2(a)), exactly as set forth below: See EX-99 CERT attached hereto.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

(Registrant)		Nuveen California Select Tax-Free Income Portfolio
By (Signature and Title)		/s/ Gifford R. Zimmerman
		Gifford R. Zimmerman
		Vice President and Secretary

Date: March 1, 2018

Pursuant to the requirements of the Securities Exchange Act of 1934 and the Investment Company Act of 1940, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the dates indicated.

By (Signature and Title)		/s/ Cedric H. Antosiewicz
		Cedric H. Antosiewicz
		Chief Administrative Officer (principal executive officer)
Date: March 1, 2018
By (Signature and Title)		/s/ Stephen D. Foy
		Stephen D. Foy
		Vice President and Controller (principal financial officer)
Date: March 1, 2018