Copied from r/prawokrwi for archival purposes. Original by u/pricklypolyglot.
This is a simple guide to the last day adult males were under the protection of the so-called military paradox, organized by birth year. The protection always lasts until Dec 31, regardless of birth month/day, unless otherwise noted. Therefore, depending on when they naturalized, they could lose Polish citizenship as soon as the following day (i.e. usually 1 Jan of the next calendar year).
Children under 18 and not subject to conscription themselves* lost citizenship along with their married father.
Therefore, if their married father naturalized, your next in line must have turned 18 or become subject to conscription by these dates.
*17 year old males were subject to conscription from 18 Nov 1924 to 27 May 1950, inclusive.
| Year of Birth | Last Day of Protection |
|---|---|
| ≥1902 | N/A |
| 1901 (18 Jan or later) | N/A |
| 1901 (1 - 17 Jan) | DOB, 1951* |
| 1900 (28 May or later) | DOB, 1950* |
| 1900 (1 Jan - 27 May) | May 27, 1950 |
| 1890 - 1899 | May 27, 1950 |
| 1889 | 31 Dec 1949 |
| 1888 | 31 Dec 1948 |
| 1887 | 31 Dec 1937** |
| ≤1886 | 31 Dec year + 50** |
*i.e. they would have lost citizenship the day after their 50th birthday.
**If they did not naturalize before 1 Sep 1938, their protection would be extended until the end of the calendar year in which they turned 60.
Last Day of Protection = citizenship lost the following day
N/A = the release from conscription occurs on or after 19 Jan 1951, therefore the ancestor could not have lost Polish citizenship through naturalization; only through public office/military service.
Sources:
Overview https://polish-citizenship.eu/military-service.html
Conscription Act of 1924 https://isap.sejm.gov.pl/isap.nsf/DocDetails.xsp?id=wdu19240610609
Conscription Act of 1938 https://isap.sejm.gov.pl/isap.nsf/DocDetails.xsp?id=WDU19380250220
Decree of February 19, 1945 (amending the Act of 1938) https://isap.sejm.gov.pl/isap.nsf/DocDetails.xsp?id=WDU19450080037
Conscription Act of 1950 https://isap.sejm.gov.pl/isap.nsf/DocDetails.xsp?id=WDU19500060046
File history:
21 Nov 2025 - added link to decree of 19 Feb 1945; minor corrections
3 April 2025 - restored previous text
2 April 2025 - removed text regarding conscription for 17 year olds pending further clarification
20 March 2025 - reworded and added (bold) text to clarify that citizenship is lost only on the following day
16 March 2025 - added note regarding the edge case of men born 1897 or earlier who naturalized on/after 2 Sep 1938
26 Feb 2025 - updated to reflect quirks for men born in 1900
25 Feb 2025 - updated to reflect wording in Act of 4 Feb 1950 (Journal of Laws No. 6, Item 46)
22 Jan 2025 - original post