Succession is the distribution of a ruler's titles upon their death based on succession and gender laws of each title.
It is one of the most important concepts in 
Crusader Kings II, as it determines which character the player controls as the heir to the primary title.
It also affects the vassals and dynasty members' opinion toward the player.
继承法
Upon a ruler's death, their titles will be distributed to other characters based upon which succession law they use. This is not necessarily the same for each title; multiple titles can follow different succession laws.
To access and see these succession laws, go to the Laws tab - Inheritance and click on the coat of arms of each title on the top.
However, it should be noted that only the succession laws of de jure titles on the highest tier the player holds matter; everything below that will be given out together with the title it is bound to.
Titles without a higher de jure title in the player's current possession will stay with their primary title.
There are several different succession laws in the game, each one with different requirements and effects. There is no 'best' succession law; which law the player will want depends upon future goals for the campaign. Below is a list of all succession laws. Succession laws consist of a type of gender and succession laws.
At duchy level and lower, a single succession law covers all of a character's titles. However, if a character holds multiple kingdom or empire titles, these will each have their own succession law. Therefore, each succession may lead to different heirs for each kingdom title hold.
Gender laws
Note that game rules can affect the implementation of gender laws.
| Inheritance | Other effects | Requirements | |
|---|---|---|---|
| Agnatic | Only males can inherit | ||
| Agnatic-Cognatic | Women can only inherit if there are no eligible males Women with sons have priority over women without sons |
Enables matrilineal marriage (if not already enabled) |
|
| Absolute Cognatic | Women inherit on equal terms with men | May grant titles to women |
|
| Enatic-Cognatic | Males can only inherit if there are no eligible women |
| |
| Enatic | Only women can inherit |
|
Succession Types
Be wary of succession laws that allow non-dynastic members to inherit, as this can result in Game over. If you are a vassal with your eyes on your liege's title, these succession laws can work in your favor. Expect AI lieges to change their succession laws as soon as a non-dynastic member or a dynasty member with a non-dynastic marriage (e.g. matrilineal if the member is male) stands to inherit. Certain succession types have Crown Authority requirements (without 
Conclave) or Administration requirements which require the Legalism technology (with Conclave).
Descriptions in italics are quotes from the in-game descriptions of the law, current as of patch version 2.3.5.
Feudal
| Law | Effect | Opinion | Requirements | ||||
|---|---|---|---|---|---|---|---|
| Oldest child | Other child | Youngest child | Dynasty | Vassal | |||
| Gavelkind | Titles distributed between all children. +30% demesne limit | -5 | +15 | +5 | +5 | Not Muslim or tribal unreformed pagan | |
| Elective gavelkind | Titles distributed between children and primary heir, who is elected from among the members of the ruling dynasty. Primary titles may be created for younger children if enough of their land is held. +30% demesne limit (mix of Tanistry and Gavelkind). Chosen successor will have +25 relations with those who've nominated them. | +15 | +5 | Not Muslim | |||
| Feudal elective (AKA Elective Monarchy) |
The ruler and vassals are given votes equal to the number of qualified titles that character holds. A successor is then voted on from among themselves and legitimate children and siblings of the ruler. Electors are happier in this system unless their liege personally holds too many elective titles.
Since non dynastic characters can be eligible nominees, it is possible to lose your top title to a non-dynasty member. Chosen successor will have +25 relations with those who've nominated them. |
-15 | -5 | -5 | +10 | Not tribal or unreformed pagan (except Hellenic). If Muslim or Eastern, must have | |
| Primogeniture | The oldest child of the ruler inherits all titles. Your successor will like the law, but other members of your dynasty will slightly disapprove.
As long as the marriage preserves the dynasty of the rule (i.e. matrilineal if the ruler is female), the dynasty will retain power of the selected title. |
+10 | -10 | -15 | -5 |
Not Muslim nor tribal nor unreformed pagan (except Bön and Hellenic). | |
| Ultimogeniture | This succession law is the opposite of the far more common Primogeniture. With Ultimogeniture, the youngest child inherits. | -15 | -10 | +10 | -5 |
Not Muslim or tribal. Not unreformed pagan (except Bön, Hellenic, and Zunist) unless culture is Mongol. | |
| Seniority | The oldest member of the dynasty inherits all titles. Your oldest child will greatly disapprove of this law, but all other members of the dynasty will approve.
Guaranteed to retain dynastic control of the title until there are no living members of the dynasty. |
-15 | -10 | +5 | -5 | Not Muslim or Eastern religion. Not tribal or unreformed pagan. Medium Crown Authority (without Conclave) | |
| Open | Child (or grandchild) with best titles inherits | -5 (only if not heir) | Muslim or  reformed pagan religion with Agnatic Clans or Enatic Clans doctrine.
| ||||
| Tanistry | The ruler and all elector vassals can nominate an heir — the Tanist — from among members of the ruler's dynasty. Vassals will tend to favor older members from other branches of the family, especially claimants
Similar to Feudal elective but with a few significant differences: candidates must be dynastic, more electors. Chosen successor will have +25 relations with those who've nominated them. |
-20 | -10 | +5 | +5 |
Celtic culture group | |
| Eldership | Similar to Tanistry, except up to six elders in the realm vote for someone in the ruler's dynasty. The six elders can have 3 states: ecstatic, pleased, or displeased. Ecstatic elders will vote for the ruler's preferred successor. Pleased elders will vote for who they want to be the successor. Displeased elders will vote for someone with very bad traits to sabotage the ruler's dynasty. Arresting or killing an elder even if justified will upset the other elders. | +5 |
| ||||
If you are about to create a kingdom title, it may be advantageous to change succession laws before the creation. So, if you're to create vassal level kings as the Byzantine Empire, your subject kingdoms will possess the laws the empire has. (Since newly created kingdoms start with the same laws as your duchies, kingdom, or empire).
Other
| Law | Effect | Requirements |
|---|---|---|
| Imperial elective | The emperor’s close family members (spouse included), any claimants to the title, the current marshal, and any commander under the emperor, can all be nominated as successors. The emperor, all of his councilors, and all of his commanders are valid electors. Each elector's voting power scales based on a number of factors:
Electors will prefer to vote for a successor with lots of titles (both minor and landed), high prestige, and who is good at their job. They will also consider factors such as age, traits (such as Imperial elective is only available to the Byzantine and Roman empires. The Byzantine Empire starts with Imperial elective succession, and can only switch to another succession style when forced by a faction (or by destroying and re-creating the empire title). |
Byzantine Empire or Roman Empire |
| 帝国选候制 | The emperor, emperor's legitimate children and siblings, along with the seven Prince-electors and any major de jure vassal of the Empire of the same religion can all be nominated as successors.
The emperor and the seven Prince-electors who are of the same religion are valid electors.
|
Holy Roman Empire |
| Open elective | The courtier with the highest sum of (age + prestige) inherits. To be eligible, a courtier must be an adult male, same religion, not heir to any other titles, and not imprisoned.
If there are no eligible courtiers with positive election scores, a new character is generated with:
For religious head titles such as The Church of Zun, courtiers are ineligible, and the title always goes to a newly generated character. For the Varangian Guard, Orthodox characters are eligible(?) even though the initial holder is Germanic pagan. |
Holy orders, mercenaries, republics, and most theocracies. Fallback for independent feudal rulers with no heir and no feudal vassals. |
| Patrician elective | Only used by merchant republics, person with most 'respect' is elected | Merchant republic |
| Investiture |
If the liege lord has nominated a successor under the free investiture law, the nominee succeeds. |
Catholic theocracy |
| Papal succession | The College of Cardinals elects the new Pope. | Only for the Papacy |
| Nomad succession |
|
 Nomadic hordes
|
| Appointment (standard) | Title reverts to liege. | Vassals of holy orders Viceroyalty vassals of empires. Fallback for feudal vassals with no heir. |
| Appointment (offmap) | The new governor will be a competent steward from China |  Western Protectorate
|
Changing succession law
Succession laws can only be changed once in a lifetime per kingdom/empire, by a ruler who:
- is at peace
- is not in a regency
- has ruled in the current capacity for 10 years. A count who has ruled for fifteen years before creating, inheriting or being granted a dukedom (or simply changing primary title) will need to wait ten more years after getting the new primary title before being allowed to change succession law.
- has no direct vassals (for counts and dukes) or direct vassals of count rank or higher (for kings and emperors) in the territory affected by the change with non-positive opinion. Since this only applies to direct vassals, a particularly troublesome vassal can sometimes be dealt with by transferring that vassal to a higher-ranked subordinate.
- does not have two or more direct vassals who are at war with each other. This can be difficult in sprawling empires. Medium crown authority helps, but does not prevent rebellions or attacks by some vassal kings. You can intervene in a prolonged war between vassals by granting one side more land. You can also stop a war immediately by revoking all counties from one combatant, or by forcing them to rebel against you.
A ruler cannot change both the succession type and the gender law.
All direct vassals and direct family members will have a large penalty or moderate bonus opinion modifier (temporary but long-lasting) as a reaction to a succession change, whether it be gender or succession method itself. This appears to be hardcoded (unmoddable) and largely arbitrary, as for example female family members will be outraged at a change to true cognatic even if it makes them the new heir, and includes baron-level vassals who in theory should have little if any opinion about it.
Note that Iqta Muslims can only use Agnatic Open (Turkish) succession (unless the "status of women" law is at the appropriate level; Muslim patricians follow the succession used in merchant republics), while Pagan tribes can only use elective gavelkind, and unreformed Pagans can only use Gavelkind (except Mongols and Zunists, who can also use Ultimogeniture, and Celtics who can use Tanistry).
Restrictions for Mongols and Aztecs
As of 2.5.1.1, some titles of Hordes are locked in a specific inheritance type which overwrite all other conditions and cannot be changed.
- Emperor of Mongol Empire is always Agnatic Gavelkind if Horse Lords DLC is not active even when he is Muslim or Republic.
- Emperor of Aztec Empire is always Agnatic Gavelkind even when he is Muslim.
Disqualification
Characters cannot inherit any titles if they are:
| Disqualification | Method |
|---|---|
| Clergy | Granting a temple, or through investiture (for Catholics) Priests of the following religions cannot inherit: Christians (except feminist heresies), Indians, Manichean, Taoist, Bön, Hellenic, and religions with the Monasticism doctrine |
Ascetic such as  or  |
Order to take the vows, or by event. |
| Members of holy orders | Send to Holy Order, or by event (for men with 5+ martial skill and with SoA enabled). |
Bastard  |
Born out of wedlock and not legitimized  . Also blocks inheritance from passing through the character. Does not block inheritance with Open succession.
|
 |
Castrate prisoner or by event |
 (for Byzantine culture group, Roman culture, Dalmatian culture) |
By decision (e.g. Blind prisoner) or by event |
| or otherwise disfigured, with Imperial elective succession |
|
| Concubine | Take concubine |
| Rulers outside the realm | (Without Conclave) High crown authority (With ) Regulated inheritance law
|
Furthermore, there are restrictions on inheritance between merchant republic titles and feudal titles. Patricians cannot inherit feudal titles, and a patrician's heir must be a courtier.
A courtier who is potential heir to conflicting titles (such as a merchant republic and a feudal duchy) will choose one or the other, rather than inheriting the title whose holder dies first. Restarting the game, and thus recalculating succession for all characters, may change these choices.
Born in the Purple (BitP; Byzantine Empire only)
The Byzantine Empire is normally locked to Imperial elective, but if re-created with another succession law, its succession is directly influenced by the 
trait and the Despot honorary title. Characters who have either of these attributes are considered higher in the succession line than those without.
- With primogeniture or gavelkind, BitP offspring take precedence over older children who were born before their parent ascended to the throne. When you have several children who are not BitP, you can pick your heir by giving one of them the Despot title.
- With seniority, BitP characters take precedence over other dynasty members as soon as they reach adulthood.
- Note that a daughter who is not BitP can take precedence over a (non-adult) BitP daughter if she has a son of her own.
- Heir designation with eastern religions in the Byzantine and Roman empires is only valid when selecting between children born in the purple.
Inheritance Conflict
When a character is already landed but inherits a new title, a conflict could occur that is indicated in the game as an alert : Vassal inheritance warning.
For example, if an English count inherits a French title from his mother upon her death, either the French or the English realm will expand as the game does not allow a character to be vassal to two different lieges.
If Crown Authority is not high enough to play a role, these conflicts are resolved as follows:
- The vassal contract that goes with the primary title stays intact. So if an English count (vassal to the King of England) inherits a French duchy (vassal to the King of France), this ducal title will be his primary title. He will become a French duke and his county will become part of France.
- Note: If the English count inherits an independent duchy, he'll become independent instead of remaining as a duke under the King of England!
- Note that the inherited title cannot be the primary title if it is of equal rank, because the heir simply never had the time to change it. (Lower ranked titles cannot be the primary title by definition.) Therefore, if an English count (vassal to the King of England) inherits a French county (vassal to the King of France), his English county will stay as his primary title and his county in France will become part of England.
You can take advantage of inheritance conflicts by arranging for your vassals to inherit foreign territory.
Fallbacks for feudal rulers with no heir
A sequence of contingency plans is used until one finds a qualified heir:
- (The ruler's succession law)
- Primogeniture
- Liege (as if succession type were Appointment)
- Feudal vassal (highest rank, with ties broken by order in landed_titles.txt ??)
- Open Elective
You may be able to take advantage of #3 to inherit your vassals' titles, or #4 to inherit the title of an independent liege.