diff --git a/Controllers/ExpenseController.cs b/Controllers/ExpenseController.cs
index d45493d..f182ea3 100644
--- a/Controllers/ExpenseController.cs
+++ b/Controllers/ExpenseController.cs
@@ -110,6 +110,10 @@ namespace FirmTracker_Server.Controllers
                 _expenseCrud.DeleteExpense(id);
                 return NoContent();
             }
+            catch (InvalidOperationException ioe)
+            {
+                return BadRequest($"{ioe.Message}");
+            }
             catch (System.Exception ex)
             {
                 return NotFound(ex.Message);
diff --git a/Controllers/ProductController.cs b/Controllers/ProductController.cs
index d7711b0..d662d96 100644
--- a/Controllers/ProductController.cs
+++ b/Controllers/ProductController.cs
@@ -148,6 +148,10 @@ namespace FirmTracker_Server.Controllers
                 _productCrud.DeleteProduct(id);
                 return NoContent();
             }
+            catch (InvalidOperationException ioe)
+            {
+                return BadRequest($"{ioe.Message}");
+            }
             catch (System.Exception ex)
             {
                 return NotFound(ex.Message);
diff --git a/Controllers/ReportController.cs b/Controllers/ReportController.cs
index fe917bb..dabcd8e 100644
--- a/Controllers/ReportController.cs
+++ b/Controllers/ReportController.cs
@@ -64,7 +64,7 @@ namespace FirmTracker_Server.Controllers
                         .Where(e => e.Date >= fromDate && e.Date <= toDate)
                         .ToList();
 
-                    
+
                     decimal totalIncome = 0;
                     foreach (var transaction in transactions)
                     {
@@ -126,7 +126,7 @@ namespace FirmTracker_Server.Controllers
 
             var options = new JsonSerializerOptions
             {
-                ReferenceHandler = ReferenceHandler.Preserve 
+                ReferenceHandler = ReferenceHandler.Preserve
             };
 
             var json = JsonSerializer.Serialize(report, options);
@@ -202,7 +202,7 @@ namespace FirmTracker_Server.Controllers
                         .Where(e => e.Date >= fromDate && e.Date <= toDate)
                         .ToList();
 
-                    
+
                     decimal totalIncome = 0;
                     foreach (var transaction in transactions)
                     {
@@ -241,7 +241,7 @@ namespace FirmTracker_Server.Controllers
             }
         }
 
-        [HttpDelete]
+        [HttpDelete("{id}")]
         [ProducesResponseType(204)]
         [ProducesResponseType(404)]
         public IActionResult DeleteReport(int id)
diff --git a/Controllers/TransactionController.cs b/Controllers/TransactionController.cs
index 3f82653..20b556e 100644
--- a/Controllers/TransactionController.cs
+++ b/Controllers/TransactionController.cs
@@ -167,6 +167,10 @@ namespace FirmTracker_Server.Controllers
                 _transactionCRUD.DeleteTransaction(id);
                 return NoContent();
             }
+            catch (InvalidOperationException ioe)
+            {
+                return BadRequest($"{ioe.Message}");
+            }
             catch (Exception ex)
             {
                 return NotFound(ex.Message);
diff --git a/nHIbernate/Expenses/ExpenseCRUD.cs b/nHIbernate/Expenses/ExpenseCRUD.cs
index c19c5e6..27096fa 100644
--- a/nHIbernate/Expenses/ExpenseCRUD.cs
+++ b/nHIbernate/Expenses/ExpenseCRUD.cs
@@ -17,6 +17,8 @@
 
 using FirmTracker_Server.nHibernate;
 using FirmTracker_Server.nHibernate.Products;
+using FirmTracker_Server.nHibernate.Reports;
+using NHibernate.Criterion;
 
 namespace FirmTracker_Server.nHibernate.Expenses
 {
@@ -102,6 +104,16 @@ namespace FirmTracker_Server.nHibernate.Expenses
                 var expense = session.Get<Expense>(expenseId);
                 if (expense != null)
                     {
+                        var criteria = session.CreateCriteria<ReportExpense>();
+                        criteria.Add(Restrictions.Eq("Expense.Id", expenseId));
+                        var reportExpenses = criteria.List<ReportExpense>();
+
+                        if (reportExpenses.Any())
+                        {
+                            throw new InvalidOperationException("Nie można usunąć wydatku. Wydatek jest ujęty w co najmniej jednym z raportów.");
+                        }
+
+
                         session.Delete(expense);
                         transaction.Commit();
                     }
diff --git a/nHIbernate/Products/ProductCRUD.cs b/nHIbernate/Products/ProductCRUD.cs
index bb2bdc3..ac06989 100644
--- a/nHIbernate/Products/ProductCRUD.cs
+++ b/nHIbernate/Products/ProductCRUD.cs
@@ -22,6 +22,9 @@ using System.Collections.Generic;
 using Microsoft.AspNetCore.OpenApi;
 using Microsoft.AspNetCore.Http.HttpResults;
 using System.Security.Cryptography.X509Certificates;
+using FirmTracker_Server.nHibernate.Reports;
+using NHibernate.Criterion;
+using FirmTracker_Server.nHibernate.Transactions;
 
 namespace FirmTracker_Server.nHibernate.Products
 {
@@ -129,6 +132,16 @@ namespace FirmTracker_Server.nHibernate.Products
                     var product = session.Get<Product>(productId);
                     if (product != null)
                     {
+
+                        var criteria = session.CreateCriteria<TransactionProduct>();
+                        criteria.Add(Restrictions.Eq("ProductID", productId));
+                        var transactionProducts = criteria.List<TransactionProduct>();
+
+                        if (transactionProducts.Any())
+                        {
+                            throw new InvalidOperationException("Nie można usunąć produktu. Produkt jest ujęty w co najmniej jednej transakcji.");
+                        }
+
                         session.Delete(product);
                         transaction.Commit();
                     }
diff --git a/nHibernate/Transactions/TransactionCRUD.cs b/nHibernate/Transactions/TransactionCRUD.cs
index 57a0221..c16d574 100644
--- a/nHibernate/Transactions/TransactionCRUD.cs
+++ b/nHibernate/Transactions/TransactionCRUD.cs
@@ -1,5 +1,7 @@
 using FirmTracker_Server.nHibernate.Products;
+using FirmTracker_Server.nHibernate.Reports;
 using NHibernate;
+using NHibernate.Criterion;
 using NHibernate.Linq;
 using System;
 using System.Collections.Generic;
@@ -177,6 +179,15 @@ namespace FirmTracker_Server.nHibernate.Transactions
                     var transaction = session.Get<Transaction>(transactionId);
                     if (transaction != null)
                     {
+                        var criteria = session.CreateCriteria<ReportTransaction>();
+                        criteria.Add(Restrictions.Eq("Transaction.Id", transactionId));
+                        var reportTransactions = criteria.List<ReportTransaction>();
+
+                        if (reportTransactions.Any())
+                        {
+                            throw new InvalidOperationException("Nie można usunąć transakcji. Transakcja jest ujęta w co najmniej jednym z raportów.");
+                        }
+
                         foreach (var transactionProduct in transaction.TransactionProducts)
                         {
                             var product = session.Get<Product>(transactionProduct.ProductID);