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A core is a province that is considered a rightful part of a country. Cores give several strategically important benefits:

  • Provinces without a core add to overextension (except colonies[1]), proportional to their development value.
  • Core provinces get a +75% positive tax modifier.
  • A country will always have a casus belli if one of their core provinces is owned by another country.
  • Some missions or decisions require certain provinces to be cored

The following actions are not allowed in uncored provinces:


States and territories

Main article: States and territories

States and territories are a new mechanic introduced in patch 1.16 intended to replace the old Overseas mechanic. The system introduces a 2-part coring process. A newly conquered province is considered as part of a territory (unless it already belongs to one of the nation's existing states). Turning a territory into a state requires that all owned provinces in the area be made "territorial cores" (which have a higher minimum autonomy, and are lost if the province is conquered); this costs half the base coring cost and takes the same amount of time. Once a state has been established, it is possible to instantaneously complete the coring process by paying the remaining coring costs. Administering development in states and territories costs governing capacity, which has a soft limit based on administrative technology.


Coring range is the same as colonial range, so it is often necessary to research diplomatic tech if expanding overseas without a land bridge. To check the range to a given province, change the map mode to "colonial range", and hover over the province of interest. The range will show, green for in range and red for out of range.

The following ideas and policies increase colonial range:

Colonial range.png Traditions Ideas Bonuses Policies
  • Exploration idea 3: Overseas Exploration
  • Hawaiian idea 7: Legendary Voyagers
  • Norwegian idea 2: The Call of our Forefathers
  • Portuguese traditions
  • Norman idea 4: Descendants of Seafarers
  • Exploration-Plutocratic: The Colonial Companies Act
  • Couronian idea 5: Couronian Colonization
  • Iwi idea 1: Sons of Kupe
  • Fijian idea 2: Lutunasobasoba and Degel

Diplomatic technology increases colonial range as seen here:

Diplomatic technology.png Diplomatic
Colonial range.png Colonial
0 +60
3 +100
7 +115
9 +50
11 +100
15 +50
17 +50
19 +50
23 +150
26 +200

Colonial range can also be increased by hiring a Navigator advisor. Note that navigator advisors can only appear if a country has at least one Colonists.png colonist envoy.

  • If a country has a core in province A, it can core every neighboring province. A doesn't have to be owned or controlled by that country.
  • If a country controls, owns and has a core in coastal province A, it can core every other coastal province that is within coring range. The ingame tooltip of requiring an "unblockaded" province is wrong, blockades do not affect this.
  • If a country controls, owns and has a core in coastal province A, then it can core any province that has a "land bridge" of owned provinces to A and is within coring distance of A.
  • If a country's vassal owns and has a core in province B, which must be on the same home continent as the country, then the country can core any province adjacent to B.
  • If a country's colonial nation owns and has a core in province C, then the country can core any province adjacent to C in all continents.

The Age of Revolutions 'Unrestricted Conquest' splendor ability allows any province to be cored, regardless of range or connection. (requires Mandate of Heaven.png Mandate of Heaven).

The Imperial authority.png Holy Roman Emperor can core any province that belongs to the empire, regardless of where it is.


The base duration for coring is 36 months. All the coring-cost modifiers apply to the coring duration, except for administrative efficiency, innovativeness, and corruption. Claims apply in a different manner, as shown below.

For example, it can be reduced by the following modifiers:

  • Adaptability idea −25% coring cost modifier
  • Country traditions or ideas that reduce coring cost (Ottomans −20% for example)
  • Choosing Shiva as personal deity of a ruler of a Hindu nation −10% (only with Wealth of Nations.png Wealth of Nations DLC)
  • Tribal Government −5% per government rank

Note: Hostile core-creation will not apply to coring duration.

These modifiers above will stack additively.

Having a claim of any type (temporary or permanent) will give a multiplicative reduction.

  • Province is claimed: −10%

A further culture bonus may be applied multiplicatively.

  • Province in same culture group than primary culture: −50%
  • Province has promoted culture: −25%

For example, if Ottomans with Kannunames (−20%) and Adaptability idea −25% is going to core a Greek (promoted culture) province with no claim, it will take 36 × (1 − 0.20 − 0.25) × (1 − 0.25) = 14 months to core.

Note: Coring takes a minimum of 6 months.

Coring progress will be halted if the province is occupied by hostile forces or when the current owner is at war with any country that already has a core on the province. Progress will resume as soon as these conditions are lifted.


It is not possible to core a province:

  • While being at war with someone who also has a core in that province. The ongoing core creation will temporarily halt if this happens.
  • While there is a missionary converting the province.
  • While a building is being constructed in the province.
  • While the culture of the province is being changed.
  • Province is occupied (Progress halts, will resume if unoccupied).
  • Province is under siege (Progress halts, will resume if siege is lifted).

Once the coring process has been started, failing the adjacency, range or land connection requirements does not revert the coring process. Coring will proceed as originally scheduled. As well, gaining or losing cost modifiers or development while coring does not change the Administrative power.png cost originally deducted nor the coring duration originally scheduled.

Gaining cores through other means

In addition to coring newly acquired provinces manually, a nation can also gain cores by diplo-annexation of vassals or integrating a junior partner of a personal union. Both processes automatically give cores on all provinces of the acquired territory, making the strategy of "feeding" vassals with uncored provinces a viable strategy to save monarch points, especially Administrative power.png administrative power. However, provinces cored this way begin with high local autonomy and will be relatively unproductive for some time, depending on government type.

When a colony becomes a city, its owner gains a free territorial core on it. If the owner has a colonial nation in the same colonial region (or becomes eligible for one with the colony finished), the core is instantly granted to the colonial nation instead (and ceded to it).

If a nation has completed Religious Ideas and is occuping a province of their religion which is owned by a nation of a different religion, they have a small chance of gaining the province as a core; a full core, even if the province is in a territory. If the province is owned by a Tengri nation who has syncretized its faith, the event can still fire.

Coring costs

Base costs

Coring is an action which costs Administrative power.pngadministrative monarch points. The base cost depend on the Development.png development of the province. For each point of development, the coring cost is 10[2] Administrative power.png administrative monarch points.


Core-creation costs are influenced by the following:

Ideas and policies:

Core-creation cost.png Traditions Ideas Bonuses Policies
  • Mughal traditions
  • Administrative idea 2: Adaptability
  • Chagatai idea 5: The Tradition of Conquest
  • Great Yuan idea 1: Da Zai Qian Yuan
  • Golden Horde idea 2: Perso-Mongol Administration
  • Horde idea 5: The Tradition of Conquest
  • Italian (cU) idea 7: The Path to Citizenship
  • Kazani idea 2: Tribal Legacy
  • Mongolian idea 4: The Northern Yuan
  • Crimean ambition
  • Anatolian traditions
  • Candarid traditions
  • Great Qing traditions
  • Karamanid traditions
  • Oirat traditions
  • Alaskan idea 3: The Secretary's Icebox
  • Aq Qoyunlu idea 3: Turko-Iranian Bureaucracy
  • Holy Roman idea 5: Roman Heritage
  • Lotharingian idea 7: Europa Universalis Imperii
  • Ottoman idea 1: Kanunnames
  • Roman idea 7: Imperium Sine Fine
  • Rûmi idea 2: Sultan al-Sharq wa al-Gharb
  • Gutnish traditions
  • Andalusian idea 5: Jund Settlements
  • Ayyubid idea 5: Rise of the Eagle
  • Brazilian idea 5: Entradas and Bandeiras
  • Dalmatian idea 7: Legacy of Illyria
  • Granada idea 2: Recover Al Andalus
  • Maratha idea 4: Office of the Peshwa
  • Manchu idea 1: United Three Jurchens
  • Ryazan idea 6: Russian Ambition
  • Tarascan idea 7: Tarascan Assimilation
  • Bosnian ambition
  • Burmese ambition
  • Herzegovinian ambition
  • Saluzzo ambition
  • Bulgarian traditions
  • Client State traditions
  • Russian traditions
  • Thomondian traditions
  • Dai Viet idea 5: Don Dien
  • Date idea 1: Oshu Shugo
  • Delhian idea 3: Restore the Delhi Empire
  • Desmondian idea 4: The Munster Ambition
  • Divine idea 2: Church Administration
  • Ethiopian idea 6: Expansionist Policy
  • Imagawa idea 7: March to Kyoto
  • Ito idea 4: Anti-Shugo Movement
  • Lunda idea 1: The Great Family
  • Manx idea 2: Kings of Mann
  • Mysorean idea 1: Unification of Mysore
  • Naxian idea 7: Naxian Ambition
  • Oda idea 2: Tenka Fubu
  • Qara Qoyunlu 2: Governor of Azerbaijan
  • Rajputana idea 1: Imperial Legacy
  • Sardinian idea 5: Piedmontese Ambition
  • Sardinian-Piedmontese idea 5: Centralized State
  • Sicilian idea 4: Greater Sicily
  • Sonoran idea 2: The Sale of Sonoran Script
  • Yamana idea 2: Grand Shugo
  • Greek ambition

Further modifiers:

Type Core-creation cost.png
Having a claim −10%
Having a permanent claim −25%
Territorial core −50%
For the Holy Roman Emperor after the reform “Reform the Hofgericht −10%
Enacting celestial reform “Establish Lifan Yuan” (requires Mandate of Heaven.png DLC) −10%
Enacting celestial decree “Expand Palace Bureaucracy” (requires Mandate of Heaven.png DLC) −10%
Tribal Government Reform “Centralize Power” (requires Dharma.png DLC) −5%
Adopt Land Acquisition Taxation Policy as an Indian Sultanate or Iqta (requires Cradle of Civilization.png DLC) −5%
Tribal despotism government form −5%/−10%/−15% for duchy/kingdom/empire rank
Assimilating Hindustani culture as Mughal (requires Dharma.png DLC) −10%
Choosing Hindu Deity Shiva Shiva as personal deity of a ruler of a Hinduism Hindu nation (requires Wealth of Nations.png Wealth of Nations DLC) −10%
Choosing Norse Deity Odin Odin as personal deity of a ruler of a Norse.png Norse nation (requires El Dorado.png El Dorado DLC) −10%
War exhaustion.png War exhaustion +3% per point
Corruption.png Corruption +1% per point
Administrative efficiency.png Administrative efficiency −1% per 1%
Enacting Promote Territorial Rights as a Coptic.png Coptic nation (requires Rights of Man.png Rights of Man DLC) −10%
Enacting Reform the Bureaucracy as a Mayan.png Mayan nation (requires El Dorado.png El Dorado DLC) −20%
Enacting Reform the Bureaucracy as an Inti.png Inti nation (requires El Dorado.png El Dorado DLC) −10%

Modifiers are summed before being applied, except the modifiers from administrative efficiency and being a territory, which are applied multiplicatively after the additive modifiers are applied.

Note: The minimum coring cost for a province before applying multiplicative modifiers is 20% of its coring cost, or 2 Administrative power per development, up to 30 development. Even with a −100% modifier on a province, the cost is still 20% of the coring cost. Also the maximum coring cost is capped at 30 development for a province. This means that if the province has 31 development, its coring cost will be treated as if it only had 30 development.

Hostile core-creation

The national ideas listed below increase coring costs for a province with a core from a nation which possesses this modifier. The increase applies even if the nation with the core does not exist. These modifiers are taken into account by the AI when making decisions on which nation to attack.

Hostile core-creation cost on us.png Traditions Ideas Bonuses Policies
  • Chickasaw idea 4: Unconquered and Unconquerable
  • Cherokee traditions
  • Dahomey traditions
  • Semien traditions
  • Chachapoyan idea 5: Chachapoyan Endurance
  • Pueblo idea 1: Ancient Pueblo Legacy

Losing cores

When negotiating a peace deal, some of the loser's cores may no longer exist afterwards:

  • As mentioned above, territorial cores in a province disappear if the province changes hands.
  • The loser can be forced to 'revoke their core' on any province they do not own and that is not of their primary culture (unless the victor owns that province and hasn't cored it themselves - probably a restriction to make working around hostile coring cost increases more difficult).
  • If the loser is forced to 'release a nation', or 'return a core' to a third nation, their cores on all provinces not of their primary culture disappear.
  • If a country is entirely destroyed, it loses all cores in provinces not of its primary culture group.

Cores in uncontrolled provinces will disappear some time after the most recent of these events:

  • The owner of the core lost ownership of the province.
  • A war between the current owner and the nation owning the core was fought.

The time to lose a core depends on the province's culture relative to the core:[3]

  • If the core is the primary nation for that province culture, or belongs to a nation that is a subject of the current owner, it will never expire.
  • If the core shares a culture group with the province culture, the base expiration duration is 150 years, else 50 years.
  • This amount of time is affected by the current owner's Absolutism.pngabsolutism, scaling up to 50% reduced duration at 100 absolutism.
  • Changing the culture in a province changes the length of the core decay timer. If a change to the length of the core decay timer means that the core would already have disappeared, then the core disappears.

Other ways to lose cores:

  • A nation can abandon a core on a province that it doesn't own (a player can do this with a button on the province view, requires Art of War.pngArt of War). However, this action also costs some Yearly prestige.pngprestige.
  • When a nation sells a province, they lose both the province and core. However, this action also costs some Yearly prestige.pngprestige.
  • When a nation releases a vassal from owned provinces, or cancels an existing subject's vassalage, they lose all cores in that subject's provinces.

Uncontested cores

A country has uncontested cores when it has cores on provinces that are owned by (part of) other countries without being at war or in a truce with those countries. They are a drain on a country's prestige: a yearly decrease of −0.1 prestige for each core province being held by another nation. Due to this prestige loss, it may be a good idea to recover such core provinces, especially if the provincial culture is already accepted in your nation.


  1. any province which was settled by colonization doesn't give overextension even if it is conquered by another country after the colony finished
  2. See in /Europa Universalis IV/common/defines.lua: PS_MAKE_PROVINCE_CORE = 10,
  3. See in /Europa Universalis IV/common/defines.lua: CORE_LOSE = 50 and CORE_LOSE_CULTURE_GROUP = 150

Ideas and Policies Idea groupsNational ideasPolicies
Ages and Institutions AgesInstitutions
Innovativeness and Technology InnovativenessTechnology