Stellaris – How to Integrate a Vassal

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Managing vassals can be tedious work. They always want more; they often nag, not to mention the threat of rebellion. One way of making those pesky vassal problems disappear is by integrating them into your own empire.

Integration is the act of stripping all systems from your subject and taking them for yourself. Sounds amazing, right? Well, there are a few things you should know about how to integrate a vassal in Stellaris.

Recommended Read: How to Explore a Wormhole in Stellaris

By the end of this guide, you will know all you need to know about changing vassal contracts, integrating vassals, how the integration process works, and which subjects are valid for integration.

To integrate a vassal in Stellaris, choose to integrate the vassal from the diplomacy screen. After paying enough influence, the vassal will become part of your empire. you need to have integration permitted as part of your vassal contract before you can integrate a vassal.


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How to Integrate a Vassal in Stellaris

Having a vassal that owns systems or resources you covet is annoying. You can’t invade them to take it away, nor can you demand they hand it over. Your only solution is to integrate their empire into your own.

Subject empires do not want to be integrated; the AI wants to win the game as much as you do, and getting integrated is a game-loss condition.

That goes the same for a player-controlled empire. If you are subject to another empire and they integrate you, the game is over.

The only way to ensure a successful takeover is to set up a vassal contract where the subject cannot refuse you.

What Is a Vassal Contract?

The vassal-subject relationship is a lot more nuanced than it seems at first glance.

It may seem like one rules over the other with an iron fist, and sometimes they do, but sometimes the vassal-overlord relationship can be symbiotic in nature.

Vassals and overlords have a contract with one another that sets out laws they both must follow.

For the overlord, this may mean providing protection, the creation of holdings, and whether the overlord provides the subject with a resource subsidy.

For a vassal, the contract determines their political freedom, whether they pay a tithe to their overlord, whether they have to help in wars, and whether they can make their own decisions or not.

Now, these terms of agreement often only benefit one party. If the terms of the deal no longer benefit the overlord, they can spend influence to alter the deal.

Vassals can only pray that their overlords do not alter the deal any further.

The more extreme the changes you enact, the greater the influence cost will be. You can counteract this by adding incentives to the deal.

For instance, if you want your subject to join your wars, you can add the promise to join in on their wars in return. This is positive for the subject and can reduce the cost of influence the overlord must pay.

For some of the most extreme contract changes, like allowing integration, adding incentives is the only way you can make the deal affordable.

Keep in mind that bad terms for the subject will reduce loyalty, and low loyalty comes with a lot of risk. Disgruntled vassals will not think twice about striking you at the first opportunity.

If you manage to negotiate integration as part of your vassal contract, another ten years must pass before you are ready to move on to the next step.

The Integration Process

With the boring bureaucracy part out of the way, you are ready to expand your empire. Taking over another empire isn’t easy; it takes time and costs a lot of influence, too.

The amount of influence you need to pay takes some simple math to work out.

There is always a base of 50, then you add the number of pops in the target empire, and finally, you add ten times the number of planets in their borders.

An easier way to express this would be: cost = 50 + pops + (10 x planets). If the target empire had 40 pops and 12 planets, the cost would be 50 + 40 + (10 x 12) = 210 influence.

You don’t pay this influence cost in one go; you must pay for it in monthly installments. From a thematic sense, this simulates the work the empires do to ensure a smooth transition of power.

In gameplay terms, all you have to do is pay five influence a month until you pay the full cost from our equation earlier.

To work out how long it will take, all you have to do is divide the influence cost by five. In our pretend scenario, it would take 42 months to pay the cost.

When you finish paying the cost of influence, the transfer is instant. All systems, pops, planets, buildings, fleets, and starbases transfer to the overlord.

The old empire ceases to be and will be forgotten when the history of the galaxy is written.


What Subjects Can You Integrate?

There are two factors that can hamper your ability to integrate your vassals. The first is the type of vassal, and the second is intergalactic laws.

Only negotiable subjects can get integrated, except for subsidiary and tributary ones. This means that only normal vassals, protectorates, and satrapy vassals are valid targets.

Creating specialized vassals like bulwarks, scholariums, or prospectoriums will exempt them from integration. So, think carefully before committing to those decisions.

That being said, these vassal options are only open to owners of the Overlord DLC.

There are also galactic laws that make the integration-permitted contract terms illegal. If the galactic community votes to enact these laws, you will not be able to integrate vassals as a member of the galactic community.

The names of the laws are: ensured sovereignty and a voice for all.

You can try to revoke the laws, or you can leave the community altogether and set out on your own.


That is everything you need to know about how to integrate vassals in Stellaris.

If you have any questions or suggestions for this guide, please let us know in the comments section below. As always, have fun integrating your vassals in Stellaris.

Simon Neve

Simon lives in Northern Ireland with his wife and two children. When not caring for his family, Simon enjoys video games, board games, and tabletop roleplaying games. When playing isn't an option he writes about them instead.

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