Estimating Foreign-Born 

Emigration Using Longitudinal 

Tax and Social Security Data

Thomas B. Foster, Anthony Knapp, and Erik Vickstrom

U.S. Census Bureau

October 26, 2022

1

Disclaimer: Any opinions and conclusions expressed herein are those of the authors and do not represent the views of the U.S. 

Census Bureau. The Census Bureau has reviewed this data product for unauthorized disclosure of confidential information and has 

approved the disclosure avoidance practices applied to this release. DRB Approval Numbers: CBDRB-FY2022-CES010-011 and 

CBDRB-FY2022-CES010-028.
Background

• Estimating emigration is challenging because of limited data.

• Previous Sources:

• Immigration and Naturalization Service, 1908 to 1957.

• Alien Address Report Program, 1952 to 1981.

• Contemporary Sources:

• U.S. Customs and Border Protection (CBP) Form I-94 Arrival/Departures.

• Social Security Administration (SSA) files.

2
Background

3

• Lacking data directly detecting emigration, “residual” methods aim to 

estimate emigration indirectly.

• Warren and Peck (1980) developed a Census-Census residual method 

to derive foreign-born emigration from population change measured 

between two decennial censuses.

• Ahmed and Robinson (1994) and Mulder et al. (2003) updated the 

rates after each census.

• Leach and Jensen (2013) replaced census data with the American 

Community Survey (ACS).
Selected Foreign-Born 

Emigration Rates from 

Prior Research

Generally, 1 to 1.5 out of 

every 100 foreign born 

emigrate per year over the 

long run.

Warren & Peck 

1.2

Van Hook et al. 

2.9

Passel et al. 

1.5

Mulder et al. 

0.9

Leach & Jensen

0.6

PEP

0.8-1.3

Ahmed & Robinson 

1.2

Schwabish

1.0-1.5

Source: Simulation of emigration rates using PEP methodology on 1-year ACS PUMS with adjustments.

Note: Figure derived from comparative analyses from Schwabish (2011) and Leach and Jensen (2013). 

4
Motivation

• Population Estimates Program (PEP) uses ACS data to estimate foreign-born 

emigration.

• Estimates derived from ACS inputs are lagged, not year-specific, and can be unstable.

• Coverage and non-coverage errors create uncertainty in the estimates.

• Ongoing work to leverage existing administrative data at the Census 

Bureau to evaluate ACS-based rates.

• Better leverage the longitudinal nature of tax data, implementing and evaluating a 

“signs-of-life” approach.

• Increase coverage of foreign-born non-filers with IRS 1099 or “information returns”.

5
Data

Data Set Variables Universe

IRS 1040s • Geography 

• Tax Year

• ITIN Flag

• Filers in U.S. 

or abroad

IRS 1099s • Geography 

• Tax Year

• Filers and 

Non-Filers in 

U.S.

Numident • Date of Birth

• Date of Death

• Country of Birth

• Year Social Security 

Number (SSN) Issued

• Foreign-Born Flag

• Individuals 

ever issued an 

SSN

• IRS 1040 federal tax returns and IRS 

1099 “information returns” (W2s, 

1098s, 1099s) 

• Tax Years 2009 through 2020

• Numident file (2022)

• Link these individual records using 

Protected Identification Keys (PIKs)

• Comparison data based on 2020 PEP 

methodology: 1

̶ Simulated emigration rates from 

ACS-ACS residual method

̶ Characteristics come from ACS proxy 

universe method

6

1 PEP methodology: https://www.census.gov/programs-surveys/popest/technical-documentation/methodology.html
Coverage Improvements & ITIN Issues

7

Coverage Previously (1040s Only) Currently (1040s and 1099s)

Best Permanent immigrants, naturalized 

citizens, non-citizen workers, refugees

Permanent immigrants, naturalized citizens, 

non-citizen workers, refugees

Limited Non-citizen students, non-citizen spouses 

and children

Non-citizen students, non-citizen spouses and 

children, non-filers, inconsistent filers

Worst Undocumented/unauthorized migrations, 

asylum seekers

Undocumented/unauthorized migrations, 

asylum seekers

None Non-filers, inconsistent filers, Non-SSNs 

(ITINs)

Non-SSNs (ITINs)

• While we do observe ITINs in the IRS 1040s and 1099s (15% of the resident foreign-born 

population, on average), unresolved issues stemming from PIK assignment remain.

• Cannot distinguish an ITIN  residual emigrant from an ITIN  SSN non-emigrant.
Previous Methodology

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Confirmed Residual Popt1 Dthst1-2 Popt2 Immt1-2

----------------Emigration----------------

Foreign-born U.S. resident 

filers (IRS 1040s, only)

Deaths among t1 ForeignBorn residents by t2

Newly arrived ForeignBorn U.S. Residents (t2)

Foreign-born U.S. 

resident filers (t1) 

filing from abroad 

at t2

Foreign-born U.S. 

resident filers (t1) 

not observed in t2

• Stable confirmed emigrant component, but erratic residual.

• Residual component includes non-emigrants who simply do not file in t2 (retirees, low 

earners, etc.)

• Requires accurate estimation of population stock and immigration component in t2.
Current Methodology

9

Popt1

Foreign-born U.S. 

residents (IRS 1040s 

or IRS 1099s)

----- Residency (T1) ----- -------------------- Migration (T2)------------------ ------- Waiting (T3) -------

Deaths

Confirmed

Residual

(potentially)

Deathst1-2

Popt2

U.S. signs of 

life (IRS 1040s 

and IRS 1099s)

Filed from 

abroad (IRS 

1040s)

No U.S. signs 

of life (IRS 

1040s 

or IRS 1099s)

Residual

No U.S. signs 

of life (IRS 

1040s 

or IRS 1099s)

Popt3

U.S. signs of 

life (IRS 1040s 

and IRS 1099s)
Emigration Rates

10

Source: ACS-ACS unadjusted residual estimates; Linked IRS 1040/1099 (TYs 2009-2020) and Numident (2022). DRB Approval 

Numbers: CBDRB-FY2022-CES010-011 & CBDRB-FY2022-CES010-028.

0.0

0.5

1.0

1.5

2.0

2.5

Emigration Rate (per 100 Foreign Born)

Emigration Interval (Calendar Years)

ACS-ACS Confirmed IRS-SSA Confirmed + Residual IRS-SSA
Emigration Rates (with Previous Estimates)

11

Source: ACS-ACS unadjusted residual estimates; Linked IRS 1040/1099 (TYs 2009-2020) and Numident (2022). DRB Approval 

Numbers: CBDRB-FY2022-CES010-011 & CBDRB-FY2022-CES010-028.

-0.5

0.0

0.5

1.0

1.5

2.0

2.5

Emigration Rate (per 100 Foreign Born)

Emigration Interval (Calendar Years)

ACS-ACS Confirmed IRS-SSA Confirmed + Residual IRS-SSA Previous Confirmed + Residual IRS-SSA
Emigration Rates by Years of Residence in U.S.

12

Note: Rates per 100 foreign-born individuals. 

Prior Studies

Years of Residence in U.S.

0-10 Years 11+ Years Total

Warren & Peck (1980) 4.4 - 1.2

Schwabish (2011) 2.3 - 1.3

Mulder et al. (2003) 0.3 1.4 0.9

Scopilliti (2011) 1.4 0.4 -

Leach & Jensen (2013) 1.3 0.2 0.6

• Most prior research finds 

that emigration rates 

decrease as years of 

residence in the U.S. 

increase:

• Those residing in the U.S. for 10 

years or fewer emigrate at rates 

between 1.3 and 4.4 percent.

• More established foreign-born 

residents (11+ years) emigrate at 

rates between 0.2 and 1.4 

percent.
Emigration Rates by Years of Residence in U.S.

13

Source: ACS-ACS unadjusted residual estimates; Linked IRS 1040/1099 (TYs 2009-2020) and Numident (2022). DRB Approval 

Numbers: CBDRB-FY2022-CES010-011 & CBDRB-FY2022-CES010-028.

0

0.5

1

1.5

2

2.5

3

3.5

4

Emigration Rate

(per 100 Foreign Born)

Emigration Interval (Calendar Years)

ACS-ACS: 0-10 Years 11+ Years

Confirmed IRS-SSA: 0-10 Years 11+ Years

Confirmed + Residual IRS-SSA: 0-10 Years 11+ Years

0-10 Years

11+ Years

Rate Ranges from 

Prior Studies
Foreign-Born Emigrants by Age: 2018-2019

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Source: Internal PEP foreign-born emigrant file; Linked IRS 1040/1099 (TYs 2016-2019) and Numident (2022). DRB Approval 

Numbers: CBDRB-FY2022-CES010-011 & CBDRB-FY2022-CES010-028.

6 6

24 24

17

15

9

3 3

14

24

22 21

14

1 2

21

22

17

19

17

0

5

10

15

20

25

30

0 to 9 10 to 17 18 to 29 30 to 39 40 to 49 50 to 64 65+

Share of Foreign-Born Emigrants (%)

ACS Proxy Universe Confirmed IRS-SSA Confirmed + Residual IRS-SSA
Foreign-Born Emigrants by Birthplace: 2018-2019

15

Source: Internal PEP foreign-born emigrant file; Linked IRS 1040/1099 (TYs 2016-2019) and Numident (2022). DRB Approval 

Numbers: CBDRB-FY2022-CES010-011 & CBDRB-FY2022-CES010-028.

40

37

12

6

3 1 1 <1

2

44

31

4

9

2 4 5

17

36

19

11

4

2

5 6

0

5

10

15

20

25

30

35

40

45

50

Mexico Asia Europe Central America

& Caribbean

Canada Oceania Africa South America

Share of Foreign-Born Emigrants (%)

ACS Proxy Universe Confirmed IRS-SSA Confirmed + Residual IRS-SSA
Foreign-Born Emigrants by State: 2018-2019

16

Source: Internal PEP foreign-born emigrant file; Linked IRS 1040/1099 (TYs 2016-2019) and Numident (2022). DRB Approval 

Numbers: CBDRB-FY2022-CES010-011 & CBDRB-FY2022-CES010-028.

25

13

9

7

4 4 3 3 3 2

29

20

7

13

6

4 5 4 4

1 2

34

21

9

12

8

5 4

3 3

2 2

31

0

5

10

15

20

25

30

35

40

CA TX NY FL IL NJ WA MA AZ GA All Others

Share of Foreign-Born Emigrants (%)

ACS Proxy Universe Confirmed IRS-SSA Confirmed + Residual IRS-SSA
Discussion

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• IRS and SSA data are not designed to measure emigration, but results 

show promise

• Improvements to previous method increase coverage and reduce 

false positives in the residual component

• “Signs-of-Life” methods take advantage of the longitudinal nature of the data

• Inclusion of IRS information returns capture non-filers and inconsistent filers

• However, clear signs of selection bias remain

• IRS-SSA distribution of emigrants skews older than ACS residual estimates

• IRS-SSA data undercount emigrants born in Mexico and leaving CA and TX

• And, declining emigration may reflect increasing coverage of tax data
Next Steps

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• Explore methods to adjust for increasing coverage of the foreign-born 

population by tax data

• Potentially incorporate additional administrative data

• Composite address or residential history files

• Medicare beneficiary data

• Kid link files

• Explore methods for incorporating the ITIN population into these 

estimates

• Mexico-born population overrepresented among those in the tax data with 

ITINs?
Thank you!

Brad Foster

Center for Economic Studies

U.S. Census Bureau

thomas.b.foster@census.gov

Anthony Knapp

Population Division

U.S. Census Bureau

anthony.knapp@census.gov

Erik Vickstrom

Center for Economic Studies

U.S. Census Bureau

erik.r.vickstrom@census.gov

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