This article may contain outdated information that is inaccurate for the current version of the game. It was last updated for Vanilla.
A core is a province that is considered a rightful part of your state. Cores give several strategically important benefits:
- Provinces without a core add to your overextension (unless it's an overseas colony), proportional to their tax base value.
- Core provinces get a +75% positive tax modifier.
- Provinces with cores will have lesser chances for revolts.
- You always have a casus belli if one of your core provinces is owned by another power.
Coring is the act of adopting a province into what is considered one's patrimony, or rightful homeland. Cored land is not considered conquered or occupied but rather a rightful part of a realm.
Coring is an action which costs administrative monarch points. The amount of points needed and therefore time it takes to core a province depends on:
- Base cost depends on base tax: for each 1 base tax, the cost is 20 AMP. (In older patches, provinces with unaccepted cultures cost more; this is no longer the case).
- An overseas province of your own culture costs 10% of the normal cost to core. Colonies automatically become cores upon completion, so this cost reduction is rarely relevant.
- War exhaustion increases coring cost by 2.5% per point.
Coring costs do not depend on:
- Your current overextension.
- The distance from your current cores.
- Your current stability.
- If you are at war or not.
Reducing core costs
The following national ideas reduce core-creation costs:
Costs are also reduced by:
- A claim on the province reduces cost by 25%.
- The third HRE reform, Reform the Hofgericht, gives 10% reduced cost for the emperor.
- The Government Type Enlightened Despotism  gives a 5% reduced cost.
Enemy core creation
The following national ideas increase coring costs for a foreign power if they conquer provinces from a nation which possesses this modifier:
- Embassy +10%
Coring is not instant. It takes 3 years, not counting any modifiers, to core a province. All the while you still have the overextension penalties to cost of stability and to your revolt risk.
When the province is occupied by rebels or a foreign power, the coring process is halted until the siege is lifted. Coring progress is also suspended when at war with a country which already has a core in the same province. Coring resumes after the war concludes.
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 the culture of the province is being changed
- if the province isn't in range. The range is the same as colonial range.
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.
- When negotiating a peace deal, a core can be removed:
- Through demanding to 'revoke core'.
- If you force a nation to 'return core's to a third nation, the nation giving away the province loses the core if the province is not of their primary culture.
- Cores in uncontrolled provinces will disappear some time after the most recent of these events:
- The province changed ownership.
- A war between the current owner and the nation owning the core was fought.
- The owner of the core lost ownership of the province.
- The time to lose a core depends on the province's culture relative to the core:[Needs verification]
- 250 years if the core is the primary tag for the province's culture.
- 100 years if the core shares a culture group with the province.
- 50 years otherwise.
- The time is doubled if the core's owner does not exist.
- If a country is destroyed, it loses all wrong-culture group cores.
- Releasing nations will remove cores from releaser if the province is not of their primary culture.