Hearts of Iron IV opens a new testing phase with the Open Beta SE™ Update 3.03, released on August 28, 2026 via Steam. The branch uses the Operation Postern v1.19.2.0.3eb1 (85f4) client.
The standard version is unchanged for now. Open beta content can still be modified or removed, and Paradox has announced no date for a move to the main branch. Players who stay on the main version will therefore not receive these adjustments yet.
Armor chassis gain new bonuses and penalties
Update 3.03 lets module statistics use separate multipliers for additive and multiplicative values. Reliability now runs from 0 to 1, corresponding to 0% to 100% according to the selected level.
Interwar tank chassis take a 5% penalty to soft attack, hard attack and air attack from the additive values of their modules. Improved, advanced and modern chassis instead receive bonuses of 5%, 10% and 12.5%, respectively. The update also changes the hit points, breakthrough and defense of several armored vehicles, tank destroyers, self-propelled guns and related units.
Motorized and mechanized formations benefit from a stronger equipment bonus: Improved Infantry Equipment I and II now provide +10% Soft Attack to those categories, up from +5%. Strategic Destruction, the Proximity Fuzes project and several tank modules also receive changes.
Modding fixes come with a localization limit
The exp, log and pow functions now handle very small and very large numbers more accurately. Paradox has also corrected a convoy-efficiency calculation in a specific configuration and an OOS desynchronization issue caused by high numerical values in mods.
Some changes display correctly only in English because the branch is not fully localized. Mod creators should check both their calculations and their text before treating the beta as stable.
How to join the Steam beta
In Steam, open Hearts of Iron IV’s properties, select Game Versions & Betas, then choose the open_beta branch. If enrollment is already active, the client update starts automatically.
Bug reports must include the version in use and be posted on the forum mentioned in official announcement. The announcement gives no price, additional platform or final release date. Players who prefer to keep the experimental changes away from their installation can remain on the main branch and follow its next developments through JEU.VIDEO homepage.
This beta chiefly concerns players tracking armor balance and mod authors. For everyone else, the practical takeaway is simple: the changes are experimental and do not affect the main version yet.
Source
- Steam Community — official announcement “HOI IV | Open Beta SE™ Update 3.03,” published on August 28, 2026.
