diff --git a/http/account.go b/http/account.go
index 77919de..ecfc409 100644
--- a/http/account.go
+++ b/http/account.go
@@ -11,10 +11,13 @@ import (
 type AccountData struct {
 	AlwaysNeededData
 	Account      *postgres.Account
+	Categories   []postgres.GetCategoriesRow
 	Transactions []postgres.GetTransactionsForAccountRow
 }
 
 func (h *Handler) account(c *gin.Context) {
+	data := c.MustGet("data").(AlwaysNeededData)
+
 	accountID := c.Param("accountid")
 	accountUUID, err := uuid.Parse(accountID)
 	if err != nil {
@@ -28,6 +31,12 @@ func (h *Handler) account(c *gin.Context) {
 		return
 	}
 
+	categories, err := h.Service.GetCategories(c.Request.Context(), data.Budget.ID)
+	if err != nil {
+		c.AbortWithError(http.StatusNotFound, err)
+		return
+	}
+
 	transactions, err := h.Service.GetTransactionsForAccount(c.Request.Context(), accountUUID)
 	if err != nil {
 		c.AbortWithError(http.StatusNotFound, err)
@@ -35,8 +44,9 @@ func (h *Handler) account(c *gin.Context) {
 	}
 
 	d := AccountData{
-		c.MustGet("data").(AlwaysNeededData),
+		data,
 		&account,
+		categories,
 		transactions,
 	}
 
diff --git a/http/budget.go b/http/budget.go
index 3b8b190..39c38b6 100644
--- a/http/budget.go
+++ b/http/budget.go
@@ -12,6 +12,7 @@ import (
 type AllAccountsData struct {
 	AlwaysNeededData
 	Account      *postgres.Account
+	Categories   []postgres.GetCategoriesRow
 	Transactions []postgres.GetTransactionsForBudgetRow
 }
 
@@ -23,6 +24,12 @@ func (h *Handler) allAccounts(c *gin.Context) {
 		return
 	}
 
+	categories, err := h.Service.GetCategories(c.Request.Context(), budgetUUID)
+	if err != nil {
+		c.AbortWithError(http.StatusNotFound, err)
+		return
+	}
+
 	transactions, err := h.Service.GetTransactionsForBudget(c.Request.Context(), budgetUUID)
 	if err != nil {
 		c.AbortWithError(http.StatusInternalServerError, err)
@@ -34,6 +41,7 @@ func (h *Handler) allAccounts(c *gin.Context) {
 		&postgres.Account{
 			Name: "All accounts",
 		},
+		categories,
 		transactions,
 	}
 
diff --git a/http/transaction.go b/http/transaction.go
index 8244842..d57266f 100644
--- a/http/transaction.go
+++ b/http/transaction.go
@@ -10,17 +10,48 @@ import (
 	"github.com/google/uuid"
 )
 
+func getUUID(c *gin.Context, name string) (uuid.UUID, error) {
+	value, succ := c.GetPostForm(name)
+	if !succ {
+		return uuid.UUID{}, fmt.Errorf("not set")
+	}
+
+	id, err := uuid.Parse(value)
+	if err != nil {
+		return uuid.UUID{}, fmt.Errorf("not a valid uuid: %w", err)
+	}
+
+	return id, nil
+}
+
+func getNullUUID(c *gin.Context, name string) (uuid.NullUUID, error) {
+	value, succ := c.GetPostForm(name)
+	if !succ {
+		return uuid.NullUUID{}, nil
+	}
+
+	id, err := uuid.Parse(value)
+	if err != nil {
+		return uuid.NullUUID{}, fmt.Errorf("not a valid uuid: %w", err)
+	}
+
+	return uuid.NullUUID{
+		UUID:  id,
+		Valid: true,
+	}, nil
+}
+
 func (h *Handler) newTransaction(c *gin.Context) {
 	transactionMemo, _ := c.GetPostForm("memo")
-	transactionAccount, succ := c.GetPostForm("account_id")
-	if !succ {
-		c.AbortWithError(http.StatusNotAcceptable, fmt.Errorf("account_id missing"))
+	transactionAccountID, err := getUUID(c, "account_id")
+	if err != nil {
+		c.AbortWithError(http.StatusNotAcceptable, err)
 		return
 	}
 
-	transactionAccountID, err := uuid.Parse(transactionAccount)
-	if !succ {
-		c.AbortWithError(http.StatusNotAcceptable, fmt.Errorf("account_id is not a valid uuid"))
+	transactionCategoryID, err := getNullUUID(c, "category_id")
+	if err != nil {
+		c.AbortWithError(http.StatusNotAcceptable, err)
 		return
 	}
 
@@ -50,7 +81,7 @@ func (h *Handler) newTransaction(c *gin.Context) {
 		Amount:     amount,
 		AccountID:  transactionAccountID,
 		PayeeID:    uuid.NullUUID{},
-		CategoryID: uuid.NullUUID{},
+		CategoryID: transactionCategoryID,
 	}
 	_, err = h.Service.CreateTransaction(c.Request.Context(), new)
 	if err != nil {
diff --git a/web/budget-new.tpl b/web/budget-new.tpl
index 50d3c6a..245c11f 100644
--- a/web/budget-new.tpl
+++ b/web/budget-new.tpl
@@ -14,7 +14,7 @@
             <div class="modal-content">
                 <div class="modal-header">
                     <h5 class="modal-title">New Budget</h5>
-                    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
+                    <button type="button" class="close" data-bs-dismiss="modal" aria-label="Close">
                         <span aria-hidden="true">&times;</span>
                     </button>
                 </div>
@@ -30,7 +30,7 @@
                         </div>
                     </div>
                     <div class="modal-footer">
-                        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
+                        <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
                         <input type="submit" class="btn btn-primary" value="Create" class="form-control" />
                     </div>
                 </form>
diff --git a/web/transaction-new.tpl b/web/transaction-new.tpl
index 30fd033..41a9a38 100644
--- a/web/transaction-new.tpl
+++ b/web/transaction-new.tpl
@@ -14,13 +14,22 @@
             <div class="modal-content">
                 <div class="modal-header">
                     <h5 class="modal-title">New Transaction</h5>
-                    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
+                    <button type="button" class="close" data-bs-dismiss="modal" aria-label="Close">
                         <span aria-hidden="true">&times;</span>
                     </button>
                 </div>
                 <form id="newtransactionform" action="/api/v1/transaction/new" method="POST">
                     <div class="modal-body">
                         <input type="hidden" name="account_id" value="{{.Account.ID}}" />
+                        <div class="form-group">
+                            <label for="category_id">Category</label>
+                            <select name="category_id" class="form-control">
+                                <option value="">-- none --</option>
+                                {{range .Categories}}
+                                    <option value="{{.ID}}">{{.Group}} : {{.Name}}</option>
+                                {{end}}
+                            </select>
+                        </div>
                         <div class="form-group">
                             <label for="date">Date</label>
                             <input type="date" name="date" class="form-control" value="{{now.Format "2006-01-02"}}" />
@@ -35,7 +44,7 @@
                         </div>
                     </div>
                     <div class="modal-footer">
-                        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
+                        <button type="button" class="btn btn-secondary" data-bs-dismiss="modal">Close</button>
                         <input type="submit" class="btn btn-primary" value="Create" class="form-control" />
                     </div>
                 </form>