diff --git a/src/auth/auth.controller.ts b/src/auth/auth.controller.ts
index f8a5ef9..7fb7b51 100644
--- a/src/auth/auth.controller.ts
+++ b/src/auth/auth.controller.ts
@@ -21,6 +21,7 @@ import { CredentialsDto } from './auth.dto';
 import { AuthService } from './auth.service';
 import { AccessPayload } from './auth.types';
 import { JwtAuthGuard } from './jwt-auth.guard';
+import { ApiProblemResponses } from '../common/decorators/api-safe-error-response.decorator';
 
 const REFRESH_COOKIE = 'refresh_token';
 const COOKIE_PATH = '/api/v1/auth';
@@ -42,6 +43,7 @@ class AuthenticationDto {
 }
 
 @ApiTags('auth')
+@ApiProblemResponses()
 @Controller('auth')
 export class AuthController {
   constructor(private readonly auth: AuthService) {}
diff --git a/src/common/decorators/api-safe-error-response.decorator.ts b/src/common/decorators/api-safe-error-response.decorator.ts
index c20a049..27db677 100644
--- a/src/common/decorators/api-safe-error-response.decorator.ts
+++ b/src/common/decorators/api-safe-error-response.decorator.ts
@@ -1,19 +1,43 @@
-import { ApiInternalServerErrorResponse, ApiProperty } from '@nestjs/swagger';
+import { applyDecorators } from '@nestjs/common';
+import {
+  ApiExtraModels,
+  ApiProperty,
+  ApiResponse,
+  getSchemaPath,
+} from '@nestjs/swagger';
 
-export class SafeErrorResponseDto {
-  @ApiProperty({ example: 500 })
-  statusCode: number;
+export class ProblemDetailsDto {
+  @ApiProperty({ example: 401 })
+  status: number;
 
-  @ApiProperty({ example: 'Internal server error' })
-  message: string;
+  @ApiProperty({ example: 'UNAUTHORIZED' })
+  code: string;
 
-  @ApiProperty({ example: '/api/v1' })
-  path: string;
+  @ApiProperty({
+    required: false,
+    example: [{ pointer: '#/email', detail: 'must be a valid email address' }],
+  })
+  errors?: { pointer: string; detail: string }[];
 }
 
-export function ApiSafeErrorResponse(): MethodDecorator & ClassDecorator {
-  return ApiInternalServerErrorResponse({
-    description: 'Internal server error',
-    type: SafeErrorResponseDto,
+function problemResponse(status: number, description: string) {
+  return ApiResponse({
+    status,
+    description,
+    content: {
+      'application/problem+json': {
+        schema: { $ref: getSchemaPath(ProblemDetailsDto) },
+      },
+    },
   });
 }
+
+export function ApiProblemResponses(): MethodDecorator & ClassDecorator {
+  return applyDecorators(
+    ApiExtraModels(ProblemDetailsDto),
+    problemResponse(400, 'Invalid request'),
+    problemResponse(401, 'Authentication required'),
+    problemResponse(404, 'Resource not found'),
+    problemResponse(500, 'Internal server error'),
+  );
+}
diff --git a/src/tbank/brokerage-accounts.controller.ts b/src/tbank/brokerage-accounts.controller.ts
index 75fc99e..60786bd 100644
--- a/src/tbank/brokerage-accounts.controller.ts
+++ b/src/tbank/brokerage-accounts.controller.ts
@@ -3,10 +3,12 @@ import { ApiBearerAuth, ApiOkResponse, ApiTags } from '@nestjs/swagger';
 import type { Request } from 'express';
 import { AccessPayload } from '../auth/auth.types';
 import { JwtAuthGuard } from '../auth/jwt-auth.guard';
+import { ApiProblemResponses } from '../common/decorators/api-safe-error-response.decorator';
 import { BrokerageAccountDto } from './brokerage-account.dto';
 import { BrokerageAccountsService } from './brokerage-accounts.service';
 
 @ApiTags('brokerage-accounts')
+@ApiProblemResponses()
 @ApiBearerAuth()
 @UseGuards(JwtAuthGuard)
 @Controller('brokerage-accounts')
diff --git a/src/tbank/portfolio.controller.ts b/src/tbank/portfolio.controller.ts
index c951ee0..6dc3d22 100644
--- a/src/tbank/portfolio.controller.ts
+++ b/src/tbank/portfolio.controller.ts
@@ -3,10 +3,12 @@ import { ApiBearerAuth, ApiOkResponse, ApiTags } from '@nestjs/swagger';
 import type { Request } from 'express';
 import { AccessPayload } from '../auth/auth.types';
 import { JwtAuthGuard } from '../auth/jwt-auth.guard';
+import { ApiProblemResponses } from '../common/decorators/api-safe-error-response.decorator';
 import { PortfolioDto } from './portfolio.dto';
 import { PortfolioService } from './portfolio.service';
 
 @ApiTags('brokerage-accounts')
+@ApiProblemResponses()
 @ApiBearerAuth()
 @UseGuards(JwtAuthGuard)
 @Controller('brokerage-accounts')
diff --git a/src/tbank/tbank-connection.controller.ts b/src/tbank/tbank-connection.controller.ts
index 8fcaab7..b780b37 100644
--- a/src/tbank/tbank-connection.controller.ts
+++ b/src/tbank/tbank-connection.controller.ts
@@ -17,6 +17,7 @@ import {
 import type { Request } from 'express';
 import { AccessPayload } from '../auth/auth.types';
 import { JwtAuthGuard } from '../auth/jwt-auth.guard';
+import { ApiProblemResponses } from '../common/decorators/api-safe-error-response.decorator';
 import {
   PutTbankConnectionDto,
   TbankConnectionStatusDto,
@@ -24,6 +25,7 @@ import {
 import { TbankConnectionService } from './tbank-connection.service';
 
 @ApiTags('tbank-connection')
+@ApiProblemResponses()
 @ApiBearerAuth()
 @UseGuards(JwtAuthGuard)
 @Controller('tbank-connection')