HOI4 MIO Guide 2026

With this guide, you’ll be able to set informed perk priorities for your Military Industrial Organizations in Hearts of Iron IV. Each section offers clear choices for various equipment types, so you can favor the best production, combat stats, and policies without memorizing every perk tree.

Quick answer

Choose production perks before combat perks

Start by selecting production-related perks for your Military Industrial Organizations before taking combat-related perks. This gives you bonuses for the entire run, not just after the war begins. Production bonuses apply as soon as factories start running, while combat perks gain value later once your army is in battle and equipment designs are locked in.

1. Prioritize production perks first Production perks give maximum value throughout the campaign 1:59
2. Combat perks come later Combat stats become important once wars begin and designs are used 2:36
3. If the perk tree offers both, choose production first Exception: Take combat stat early if a specific equipment type needs it 2:55

Rank production buffs by value

Not all production bonuses are equal. Here’s how to rank them when picking perks:

Use two MIOs when design and production perks differ

Equipment lines can be assigned both a design MIO and a production MIO. This lets you use one organization for powerful production bonuses and another for stronger combat stats if their perk trees differ.

1. Assign a design MIO for combat stats Design slot perks boost breakthrough, defense, attack, etc. 5:40
2. Assign a production MIO for output Production slot perks give cap, output, and cost bonuses 5:46
3. Combine perks if one MIO tree lacks good stats Use dual MIO assignment for best bonuses 6:32
4. Be aware of slower perk unlocks Dual MIO use slows perk progression significantly 7:08

Pick infantry and support equipment perks by mode

For infantry equipment, your priorities change based on game mode:

• In single player, soft attack is the primary combat stat after production perks. Soft attack strongly affects how much damage your divisions deliver to enemy troops.
• Breakthrough is also valuable for infantry and should be taken as a secondary stat.
• In multiplayer, hard attack and piercing are much more important, as opponents frequently use tanks. Boosting these early will make your infantry effective against armored divisions.
• By the time you reach around 11 MIO perks, production issues are usually solved. If you still have production shortages, skip any perks with negative production effects.
• Support equipment MIO perks are usually only valuable when they apply to support equipment itself. For infantry equipment, use the infantry MIO tree instead.
• Early support equipment research bonus perks are useful and speed up tech unlocks, especially if you focus on supports like logistics or signals.

Pick tank perks by tank role

Tank perk priorities depend on the division role:

• Infantry tanks: Focus on reliability and breakthrough after production bonuses. Speed tends to be less important in mixed divisions with infantry since they only move as fast as their slowest component.
• Motorized and mechanized tanks: Speed becomes crucial—perks granting extra speed should be taken early.
• The standard perk order: production bonuses first, then reliability for infantry tanks and speed for motorized/mechanized. Breakthrough should be taken when your line needs it, especially for offensive divisions.
• For single player, soft attack is most important after production buffs; in multiplayer, hard attack and piercing matter more.
• The infantry tank designer usually gives substantial soft attack and unlocks these perks early—great for most runs.
• The fast tank designer delivers good speed but its production cap bonus appears late, so only use if you need maximum speed.
• Heavy tank designers are generally only relevant in multiplayer where armored divisions are prioritized.
• Assault guns lose too much soft attack compared to the infantry tank designer, making them a weaker pick outside light tank builds.
• Standardized production perks are strong, but not the best overall tank MIO—consider the infantry tank designer for most games.

Pick the right navy MIO for your fleet

The best navy MIO is typically Raiding Shipbuilders:

• Raiding Shipbuilders outperforms most other naval organizations in nearly all scenarios and ship types.
• After production perks, surface visibility reduction is the top stat for ships. Lower visibility means your ships avoid detection, engage on their terms, and survive longer.
• For capital ships (battleships, carriers), pathing differs compared to screens and submarines. Prioritize perks differently depending on your fleet setup.
• Speed is valuable for all ships, reducing the chance of being hit during combat.
• Screens benefit from torpedo attack—the right MIO can boost this, making destroyers much more potent.
• Escort Shipbuilders add considerable light attack, an asset for cruisers and destroyers.
• Carrier-focused MIOs grant carrier HP, anti-air, speed, and armor. They are situational, but rarely outperform Raiding Shipbuilders.
• Battleline Shipbuilders are viable for battleships but lack strong visibility reduction and output perks.
• Submarine MIOs are good for subs but usually weaker than Raiding Shipbuilders—even in pure submarine fleets.

Pick plane perks by aircraft type

For aircraft MIOs, tailor the perks to your plane type:

• For fighters, prioritize air attack first—this is their main offensive stat and determines air superiority.
• For Close Air Support (CAS), ground attack is the key stat.
• For naval bombers, focus on surface detection and naval attack to maximize fleet damage.
• Secondary stat order for fighters: air defense, agility, speed, reliability. Agility helps dogfighting, speed extends operational range, reliability is mostly negligible for planes.
• Medium aircraft follow the same stat order as lighter planes, though some range-focused designers offer superior bonuses.
• Range-focused designers (like Germany’s Focke-Wulf) can deliver +10% range and +10% air attack immediately. With just three perks, you can hit +20% range.
• The later +15% range perk is available once advanced machine tools are researched.
• Italy’s range-centric designer has fewer perks than Germany’s equivalent, making it somewhat less potent.

Pick policies for cap, gain, and materials

Policies can’t be saved for later, so manage perk assignments to unlock them when needed. You can leave one or more perks unassigned to delay the policy choice until the right moment.

• Assembly line optimizers is a reliable default policy—boosting both efficiency cap and efficiency gain for all production.
• Vertical integration is essential for large navies, as it reduces required materials by 10%. It’s also valuable for air power, especially when rubber is scarce.
• Some policies expand which equipment types a given MIO can be assigned to—for example, allowing a tank MIO to buff heavy tanks or a shipbuilder MIO to apply to carriers.

Remember the main default picks

Keep these defaults in mind for faster decisions and optimal outcomes:

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