As of 2018[update], at least three players under 21 years of age must play in each match, and only two foreign nationals are permitted to play for each team.[5]
Since its inception in 1992, the league has changed formats several times. In its inaugural season, the league had four divisions (North, Center, South and West). In the 1992–93 season, a fifth division was added (East). The five-group league continued until the 2006–07 season when the league was re-organised and reduced to three geographical divisions with 18 clubs in each group.[citation needed]
As of 2018, teams are promoted only if they have a valid license to the 2.HNL. For example,NK Vinogradar won the 2017, 2018 and 2019 west division, but were denied promotion since they did not apply for a license.[6]
From the season 2022–23 onward, it is a unified league just as the top two tiers.
1. a : Although Hrvatski Vitez of Posedarje finished top of the 1999–2000 South Division, they were demoted for unknown reasons and competed in the 4th league the following season. South Division runners-upImotska Krajina were promoted to 2. HNL instead.
2. a : AlthoughNK Hrvace finished top of the 2007–08 South Division, they did not applied for promotion so South Division runners-upJunak of Sinj were promoted to 2. HNL instead.
3. a : Although NK Grafičar Vodovod finished top of the 2008–09 East Division, they did not applied for promotion. As only fifth placedNK Vukovar '91 met the needed criteria they were promoted to 2. HNL instead.
4. a : AlthoughNK Lipik finished top of the 2009–10 East Division, they did not applied for promotion so East Division runners-upMV Croatia of Slavonski Brod were promoted to 2. HNL instead.
5. a : AlthoughNK Podravina Ludbreg finished top of the 2010–11 East Division and applied for promotion, they subsequently refused promotion for financial reasons. No one from East Division was promoted to 2. HNL instead.
6. a : AlthoughNK Raštane finished top of the 2010–11 South Division, their application for 2. HNL was refused because of lack of appropriate infrastructure. No one from South Division was promoted to 2. HNL instead.
7. a : AlthoughNK BSK Bijelo Brdo finished top of the 2011–12 East Division, they did not applied for promotion. No one from East Division was promoted to 2. HNL instead.
8. a : AlthoughNK Mladost Ždralovi finished top of the 2011–12 North Division, they did not applied for promotion. No one from North Division was promoted to 2. HNL instead.
9. a : AlthoughNK Raštane finished top of the 2011–12 South Division, they did not applied for promotion so South Division runners-upNK Primorac 1929 were promoted to 2. HNL instead.
10. a : AlthoughGrobničan finished top of the 2012–13 West Division, they did not apply for promotion. No one from West Division was promoted to 2. HNL instead.
11. a : AlthoughSlavonija finished top of the 2012–13 East Division, their application for 2. HNL was refused because of lack of appropriate infrastructure. No one from East Division was promoted to 2. HNL instead.
12. a : AlthoughNK Mladost Ždralovi finished top of the 2012–13 North Division, they did not apply for promotion. No one from North Division was promoted to 2. HNL instead.
14. a : AlthoughMaksimir,Opatija andBSK Bijelo Brdo finished top of their respective 2013–14 divisions, they did not apply for promotion.Međimurje, champion of 3. HNL North Division, applied for promotion but did not met necessary financial and infrastructural requirements.
15. a : AlthoughNK Vinogradar finished top of the 2016–17 West Division, they did not apply for promotion so West Division runners-upNK Kustošija Zagreb gained promotion to 2. HNL.
16. a : AlthoughNK Međimurje finished top of the 2016–17 East Division, they did not apply for promotion so East Division runners-upNK Varaždin gained promotion to 2. HNL.
17. a : AlthoughNK Vinogradar andNK Opatija finished on top of the 2017–18 West Division, they were not promoted as they were not granted a licence for 2. HNL.
18. a : AlthoughNK Croatia Zmijavci andHNK Primorac Biograd na Moru finished on top of the 2017–18 South Division, they were not promoted as they were not granted a licence for 2. HNL. Third placedNK Zadar gained promotion to 2. HNL.
19. a : AlthoughNK Vinogradar finished on top of the 2018–19 West Division, they were not promoted as they were not granted a licence for 2. HNL. Second placedNK Dubrava and third placedHNK Orijent 1919 gained promotion to 2. HNL.