diff --git a/client b/client
index fc716f66..09d1f5b4 160000
--- a/client
+++ b/client
@@ -1 +1 @@
-Subproject commit fc716f6673fba40b3d088285be923a9acdfff612
+Subproject commit 09d1f5b448a39f8c87560b7ddd4455c19f35a97d
diff --git a/client-gui2 b/client-gui2
index e4f6e8a7..3731e19a 160000
--- a/client-gui2
+++ b/client-gui2
@@ -1 +1 @@
-Subproject commit e4f6e8a76f447d9421a8dc4f2cc87bf030bd5bd8
+Subproject commit 3731e19a49e5bd48d74056cdb2455d0ae0c65e1f
diff --git a/common/proto/table_definition.proto b/common/proto/table_definition.proto
index da27436c..66c0591e 100644
--- a/common/proto/table_definition.proto
+++ b/common/proto/table_definition.proto
@@ -140,6 +140,7 @@ message SetModuleConfigurationRequest {
   // Initializes an existing profile's bookkeeping currency. Empty leaves it unchanged.
   // Defaults scope and changes to an already configured currency are rejected.
   string accounting_currency = 3;
+  repeated ModuleDataAccessUpdate data_access_updates = 4;
 }
 
 message ModuleConfiguration {
@@ -148,6 +149,31 @@ message ModuleConfiguration {
   repeated string selected_modules = 3;
   repeated string effective_modules = 5;
   string accounting_currency = 6;
+  repeated ModuleDataAccessRequest data_access_requests = 7;
+}
+
+enum ModuleDataPermission {
+  MODULE_DATA_PERMISSION_UNSPECIFIED = 0;
+  MODULE_DATA_PERMISSION_ACCOUNTING_PERIOD_BALANCES = 1;
+}
+
+enum ModuleDataAccessDecision {
+  MODULE_DATA_ACCESS_DECISION_UNSPECIFIED = 0;
+  MODULE_DATA_ACCESS_DECISION_ALLOW = 1;
+  MODULE_DATA_ACCESS_DECISION_REVOKE = 2;
+}
+
+message ModuleDataAccessRequest {
+  string requesting_module = 1;
+  string providing_module = 2;
+  ModuleDataPermission permission = 3;
+  bool granted = 4;
+}
+
+message ModuleDataAccessUpdate {
+  string requesting_module = 1;
+  ModuleDataPermission permission = 2;
+  ModuleDataAccessDecision decision = 3;
 }
 
 message CreateCustomExchangeRatesTableRequest {
diff --git a/common/src/proto/descriptor.bin b/common/src/proto/descriptor.bin
index 963f5a0c..b931c2a8 100644
Binary files a/common/src/proto/descriptor.bin and b/common/src/proto/descriptor.bin differ
diff --git a/common/src/proto/komp_ac.table_definition.rs b/common/src/proto/komp_ac.table_definition.rs
index 3dbd3048..60f7a7f1 100644
--- a/common/src/proto/komp_ac.table_definition.rs
+++ b/common/src/proto/komp_ac.table_definition.rs
@@ -40,7 +40,7 @@ pub struct GetModuleConfigurationRequest {
 }
 /// Profile updates require an existing profile. Defaults affect future profiles only.
 #[derive(serde::Serialize, serde::Deserialize)]
-#[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
+#[derive(Clone, PartialEq, ::prost::Message)]
 pub struct SetModuleConfigurationRequest {
     #[prost(message, optional, tag = "1")]
     pub scope: ::core::option::Option<ModuleScope>,
@@ -50,9 +50,11 @@ pub struct SetModuleConfigurationRequest {
     /// Defaults scope and changes to an already configured currency are rejected.
     #[prost(string, tag = "3")]
     pub accounting_currency: ::prost::alloc::string::String,
+    #[prost(message, repeated, tag = "4")]
+    pub data_access_updates: ::prost::alloc::vec::Vec<ModuleDataAccessUpdate>,
 }
 #[derive(serde::Serialize, serde::Deserialize)]
-#[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
+#[derive(Clone, PartialEq, ::prost::Message)]
 pub struct ModuleConfiguration {
     #[prost(message, optional, tag = "1")]
     pub scope: ::core::option::Option<ModuleScope>,
@@ -64,6 +66,30 @@ pub struct ModuleConfiguration {
     pub effective_modules: ::prost::alloc::vec::Vec<::prost::alloc::string::String>,
     #[prost(string, tag = "6")]
     pub accounting_currency: ::prost::alloc::string::String,
+    #[prost(message, repeated, tag = "7")]
+    pub data_access_requests: ::prost::alloc::vec::Vec<ModuleDataAccessRequest>,
+}
+#[derive(serde::Serialize, serde::Deserialize)]
+#[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
+pub struct ModuleDataAccessRequest {
+    #[prost(string, tag = "1")]
+    pub requesting_module: ::prost::alloc::string::String,
+    #[prost(string, tag = "2")]
+    pub providing_module: ::prost::alloc::string::String,
+    #[prost(enumeration = "ModuleDataPermission", tag = "3")]
+    pub permission: i32,
+    #[prost(bool, tag = "4")]
+    pub granted: bool,
+}
+#[derive(serde::Serialize, serde::Deserialize)]
+#[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
+pub struct ModuleDataAccessUpdate {
+    #[prost(string, tag = "1")]
+    pub requesting_module: ::prost::alloc::string::String,
+    #[prost(enumeration = "ModuleDataPermission", tag = "2")]
+    pub permission: i32,
+    #[prost(enumeration = "ModuleDataAccessDecision", tag = "3")]
+    pub decision: i32,
 }
 #[derive(serde::Serialize, serde::Deserialize)]
 #[derive(Clone, PartialEq, Eq, Hash, ::prost::Message)]
@@ -1121,6 +1147,67 @@ pub mod list_column_types_response {
 #[derive(serde::Serialize, serde::Deserialize)]
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, ::prost::Enumeration)]
 #[repr(i32)]
+pub enum ModuleDataPermission {
+    Unspecified = 0,
+    AccountingPeriodBalances = 1,
+}
+impl ModuleDataPermission {
+    /// String value of the enum field names used in the ProtoBuf definition.
+    ///
+    /// The values are not transformed in any way and thus are considered stable
+    /// (if the ProtoBuf definition does not change) and safe for programmatic use.
+    pub fn as_str_name(&self) -> &'static str {
+        match self {
+            Self::Unspecified => "MODULE_DATA_PERMISSION_UNSPECIFIED",
+            Self::AccountingPeriodBalances => {
+                "MODULE_DATA_PERMISSION_ACCOUNTING_PERIOD_BALANCES"
+            }
+        }
+    }
+    /// Creates an enum from field names used in the ProtoBuf definition.
+    pub fn from_str_name(value: &str) -> ::core::option::Option<Self> {
+        match value {
+            "MODULE_DATA_PERMISSION_UNSPECIFIED" => Some(Self::Unspecified),
+            "MODULE_DATA_PERMISSION_ACCOUNTING_PERIOD_BALANCES" => {
+                Some(Self::AccountingPeriodBalances)
+            }
+            _ => None,
+        }
+    }
+}
+#[derive(serde::Serialize, serde::Deserialize)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, ::prost::Enumeration)]
+#[repr(i32)]
+pub enum ModuleDataAccessDecision {
+    Unspecified = 0,
+    Allow = 1,
+    Revoke = 2,
+}
+impl ModuleDataAccessDecision {
+    /// String value of the enum field names used in the ProtoBuf definition.
+    ///
+    /// The values are not transformed in any way and thus are considered stable
+    /// (if the ProtoBuf definition does not change) and safe for programmatic use.
+    pub fn as_str_name(&self) -> &'static str {
+        match self {
+            Self::Unspecified => "MODULE_DATA_ACCESS_DECISION_UNSPECIFIED",
+            Self::Allow => "MODULE_DATA_ACCESS_DECISION_ALLOW",
+            Self::Revoke => "MODULE_DATA_ACCESS_DECISION_REVOKE",
+        }
+    }
+    /// Creates an enum from field names used in the ProtoBuf definition.
+    pub fn from_str_name(value: &str) -> ::core::option::Option<Self> {
+        match value {
+            "MODULE_DATA_ACCESS_DECISION_UNSPECIFIED" => Some(Self::Unspecified),
+            "MODULE_DATA_ACCESS_DECISION_ALLOW" => Some(Self::Allow),
+            "MODULE_DATA_ACCESS_DECISION_REVOKE" => Some(Self::Revoke),
+            _ => None,
+        }
+    }
+}
+#[derive(serde::Serialize, serde::Deserialize)]
+#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, ::prost::Enumeration)]
+#[repr(i32)]
 pub enum InvoiceTemplateAccountingRole {
     Unspecified = 0,
     InvoiceTemplateAccountingName = 1,
diff --git a/server b/server
index 7a2f9372..5e28c7fe 160000
--- a/server
+++ b/server
@@ -1 +1 @@
-Subproject commit 7a2f937242efbba365025a99cac7508b0a247280
+Subproject commit 5e28c7fe06a4b5fb58e3c01ddf6cc5f6374f4c3b