# US Nonimmigrant Visa Holder Estimates & Overstay Modeling (Dec 2025) ## Primary Official Sources - DHS OHSS: *Population Estimates for Nonimmigrants Residing in the United States* (latest FY 2024, Aug 2025) - DHS: *Entry/Exit Overstay Report* (latest FY 2023) - DOS: *Report of the Visa Office* (FY 2024 full, FY 2025 monthly) - USCIS: Quarterly petitions approved & Employer Data Hub ## Types of Visas 1. Diplomatic & Official - A-1 - A-2 - A-3 - G-1 - G-2 - G-3 - G-4 - G-5 - NATO-1 to NATO-7 2. Business & Tourism - B-1 - B-2 3. Transit & Crew - C-1 - C-1/D - C-2 - C-3 - D-1 4. Treaty Trader/Investor - E-1 - E-2 - E-2C - E-3 5. Students - F-1 - F-2 - F-3 - M-1 - M-2 - M-3 6. Exchange Visitors - J-1 - J-2 - Q-1 - Q-2 - Q-3 7. Specialty Occupations - H-1B - H-1B1 - H-1C 8. Temporary Workers - H-2A - H-2B - H-3 - H-4 9. Intracompany Transferees - L-1A - L-1B - L-2 10. Media & Journalists - I 11. Fiancé(e) & Family - K-1 - K-2 - K-3 - K-4 - V-1 - V-2 - V-3 12. Religious Workers - R-1 - R-2 13. Extraordinary Ability - O-1A - O-1B - O-2 - O-3 14. Athletes & Entertainers - P-1A - P-1B - P-2 - P-3 - P-4 15. Victims of Trafficking/Crime - T-1 to T-6 - U-1 to U-5 16. NAFTA/TN Professionals - TN - TD 17. Special Immigrant/Informant - S-5 - S-6 - S-7 18. Parent/Child of Special Immigrants - N-8 - N-9 ## 1. Cohort-Component Model (Active Holders) $P_t = P_{t-1} + I_t - O_t - D_t + A_t$ Where: - $P_t$ = active population at current time $t$ - $I_t$ = inflows (new issuances + admissions) - $O_t$ = departures (estimated from prior cohorts) - $D_t$ = adjustments to LPR or removals - $A_t$ = extensions/renewals Typical durations: - H-1B: average 5.5 years (max 6) - H-2A: average 9 months (highly seasonal) Baseline (DHS FY 2024): - H-1B ≈ 583 000 active - H-2A peak ≈ 300 000 active --- ### "Estimated from prior cohorts" – Exact Meaning In the cohort-component model, the departures term $O_t$ is **not measured directly in real time** for every individual. Instead, it is **estimated from prior cohorts** using the following method: #### Definition Take every group of people who entered the U.S. on the same visa class in a past year $t-k$ (a “cohort”) and calculate how many actually left on time using historical I-94 matched records. That observed departure fraction is then applied to the surviving members of each cohort still present in year $t$. #### Mathematical Form (simplified) $ O_t = \sum_{k=1}^{k_{\text{max}}} \left( I_{t-k} \times (1 - r_k) \times s_{t,k} \right) $ Where: - $I_{t-k}$ = inflows (admissions/issuances) in year $t-k$ - $r_k$ = overstay rate observed for that cohort after $k$ years - $s_{t,k}$ = survival fraction of the cohort still legally present at time $t$ (accounts for earlier departures, adjustments, etc.) - $k_{\text{max}}$ = maximum allowed duration of the visa class #### Concrete Examples ##### H-1B (max 6 years) $ O_{2025} \approx (I_{2019} \times 0.985) + (I_{2020} \times 0.97) + \cdots + (I_{2024} \times 0.70) $ (using observed departure rates per cohort year) ### H-2A (typically ≤ 10 months) $ O_{2025} \approx I_{2024} \times (1 - 0.03) \approx I_{2024} \times 0.97 $ --- <p align="justify"><b>Note:</b> Standards for calculations are derived from the DHS/USCIS methodology to solve for “estimated from prior cohorts” in the departures term of the population formula.</p> Referenced from *[U.S. Nonimmigrant Admissions: 2023](https://ohss.dhs.gov/sites/default/files/2024-09/2024_0906_ohss_nonimmigrant_fy2023_0.pdf)* published by the Office of Homeland Security Statistics. Authored by Aneer Rukh-Kamaa. <div style="left: 0; width: 100%; height: 0; position: relative; padding-bottom: 60%;"><iframe src="https://docs.google.com/viewer?embedded=true&url=http://sbik.site.nfoservers.com/PDFs/Topics_A-Z/Visas-and-Census_Dec2025/US-Nonimmigrant_Admissions-2023.pdf" style="top: 0; left: 0; width: 100%; height: 100%; position: absolute; border: 0;" allowfullscreen></iframe></div> From the Text (page 3): - In 2023, DHS granted an estimated 132 million nonimmigrant admissions to the United States (Figure 1). - These included 68 million admissions of nonimmigrants who were issued Form I-94, the primary focus of this report. - Nonimmigrant admissions in 2023 increased **<span style="background:rgba(3, 135, 102, 0.2)">52 percent</span>** from 2022. ## 2. Residual Overstay Model (Visa Overstays) $U = \sum_c (V_c \times r_c \times s_c)$ Where: - $V_c$ = cumulative admissions/issuances in class $c$ over look-back window (FY2023) - $r_c$ = overstay rate (DHS FY 2023: H-1B ≈ 1.5 %, H-2A ≈ 2–3 %) - $s_c$ = survival fraction still undocumented (≈ 60–70 % per CMS) DHS historical split: ≈ 62 % of new undocumented entrants are visa overstays. ## 3. Bayesian Updating (Uncertainty Modeling) Prior ← DHS official estimate Likelihood ← overstay rates + petition approvals Posterior ← updated count + 95 % credible interval Implementation: PyMC3 / PyMC (Python) or Stan. ## Framework Comparison | Framework | Key Inputs | Output | Pros | Cons | |--------------------|-------------------------------------|----------------------------|------------------------------|------------------------------| | Cohort-Component | Issuances, durations, rates | Active holders by month | Captures dynamics | Requires monthly/quarterly data | | Residual | Total undocumented, EWI split | Overstay undocumented | Simple stock estimate | Assumes stable rates | | Bayesian | DHS priors + overstay likelihood | Estimate + CI | Quantifies uncertainty | Computationally heavier | ## Query Strategy (Exact Search Strings) - `"DHS nonimmigrant population estimates FY 2025" site:dhs.gov` - `"Entry/Exit Overstay Report FY 2023" H-1B OR H-2A site:dhs.gov` - `"Report of the Visa Office" "Table XVI" FY 2025 site:travel.state.gov` - `"USCIS H-1B petitions approved" FY 2025 site:uscis.gov` ## Accuracy Target Using the above methods and official sources: 90–95 % alignment with final DHS releases when they publish (typically Q3 following fiscal year).