diff --git a/api/src/graphql/monthlyBudgets.sdl.ts b/api/src/graphql/monthlyBudgets.sdl.ts
new file mode 100644
index 0000000..ca39a21
--- /dev/null
+++ b/api/src/graphql/monthlyBudgets.sdl.ts
@@ -0,0 +1,31 @@
+export const schema = gql`
+  type MonthlyBudgetCategory {
+    id: String!
+    name: String!
+    month: Int!
+    year: Int!
+    assigned: Float!
+    activity: Float!
+    available: Float!
+  }
+
+  type MonthlyBudgetGroup {
+    id: String!
+    name: String!
+    month: Int!
+    year: Int!
+    assigned: Float!
+    activity: Float!
+    available: Float!
+    subRows: [MonthlyBudgetCategory!]
+  }
+
+  type Query {
+    monthlyBudget(
+      id: String!
+      userId: String!
+      month: Int!
+      year: Int!
+    ): [MonthlyBudgetGroup!]! @requireAuth
+  }
+`
diff --git a/api/src/services/monthlyBudgets/monthlyBudgets.ts b/api/src/services/monthlyBudgets/monthlyBudgets.ts
new file mode 100644
index 0000000..08e78b6
--- /dev/null
+++ b/api/src/services/monthlyBudgets/monthlyBudgets.ts
@@ -0,0 +1,111 @@
+import type {
+  MonthlyBudgetGroupRelationResolvers,
+  QueryResolvers,
+} from 'types/graphql'
+
+import { db } from 'src/lib/db'
+
+export const monthlyBudget: QueryResolvers['monthlyBudget'] = async ({
+  id,
+  userId,
+  month,
+  year,
+}) => {
+  const query = await db.budget.findUnique({
+    where: {
+      id,
+      userId,
+    },
+    include: {
+      budgetCategoryGroups: {
+        orderBy: {
+          sortOrder: 'asc',
+        },
+        include: {
+          monthlyCategoryGroupActivities: {
+            where: {
+              month,
+              year,
+            },
+          },
+          budgetCategories: {
+            orderBy: {
+              sortOrder: 'asc',
+            },
+            include: {
+              monthlyBudgetPerCategories: {
+                where: {
+                  month,
+                  year,
+                },
+                include: {
+                  monthlyCategoryActivity: true,
+                },
+              },
+            },
+          },
+        },
+      },
+    },
+  })
+
+  const res = query.budgetCategoryGroups.map((group) => {
+    return {
+      id: group.id,
+      name: group.name,
+      month,
+      year,
+      assigned:
+        group.monthlyCategoryGroupActivities[0]?.assigned.toNumber() || 0,
+      activity:
+        group.monthlyCategoryGroupActivities[0]?.activity.toNumber() || 0,
+      available:
+        group.monthlyCategoryGroupActivities[0]?.available.toNumber() || 0,
+    }
+  })
+
+  return res
+}
+
+export const MonthlyBudgetGroup: MonthlyBudgetGroupRelationResolvers = {
+  subRows: async (_obj, { root }) => {
+    const categoryGroups = await db.budgetCategoryGroup.findUnique({
+      where: { id: root.id },
+      include: {
+        budgetCategories: {
+          orderBy: {
+            sortOrder: 'asc',
+          },
+          include: {
+            monthlyBudgetPerCategories: {
+              where: {
+                month: root.month,
+                year: root.year,
+              },
+              include: {
+                monthlyCategoryActivity: true,
+              },
+            },
+          },
+        },
+      },
+    })
+
+    return categoryGroups.budgetCategories.map((category) => {
+      return {
+        id: category.id,
+        name: category.name,
+        month: root.month,
+        year: root.year,
+        assigned:
+          category.monthlyBudgetPerCategories[0]?.assigned.toNumber() || 0,
+        activity:
+          category.monthlyBudgetPerCategories[0]?.monthlyCategoryActivity.activity.toNumber() ||
+          0,
+        available:
+          category.monthlyBudgetPerCategories[0]?.monthlyCategoryActivity.available.toNumber() ||
+          0,
+      }
+    })
+  },
+}
diff --git a/web/src/components/MonthlyBudgetsCell/MonthlyBudgetsCell.tsx b/web/src/components/MonthlyBudgetsCell/MonthlyBudgetsCell.tsx
index 8e7beb5..9e5cb73 100644
--- a/web/src/components/MonthlyBudgetsCell/MonthlyBudgetsCell.tsx
+++ b/web/src/components/MonthlyBudgetsCell/MonthlyBudgetsCell.tsx
@@ -9,8 +9,6 @@ import {
   DataTableSkeleton,
 } from 'src/components/Spreadsheet/data-table'
 
-import { convertBudgetGQLIntoDisplayable } from './convertData'
-
 export const QUERY = gql`
   query FindBudgetByMonth(
     $userId: String!
@@ -18,30 +16,18 @@ export const QUERY = gql`
     $month: Int!
     $year: Int!
   ) {
-    budget(id: $budgetId, userId: $userId) {
-      budgetCategoryGroups {
+    monthlyBudget(id: $budgetId, userId: $userId, month: $month, year: $year) {
+      id
+      category: name
+      assigned
+      activity
+      available
+      subRows {
         id
-        name
-        sortOrder
-        monthlyCategoryGroupActivity(month: $month, year: $year) {
-          assigned
-          activity
-          available
-        }
-        budgetCategories {
-          id
-          name
-          sortOrder
-          monthlyBudgetPerCategory(month: $month, year: $year) {
-            month
-            year
-            assigned
-            monthlyCategoryActivity {
-              activity
-              available
-            }
-          }
-        }
+        category: name
+        assigned
+        activity
+        available
       }
     }
   }
@@ -57,11 +43,8 @@ export const Failure = ({ error }: CellFailureProps) => (
   <div style={{ color: 'red' }}>Error: {error?.message}</div>
 )
 
-export const Success = ({ budget }: CellSuccessProps<FindBudgetByMonth>) => {
-  return (
-    <DataTable
-      columns={columns}
-      data={convertBudgetGQLIntoDisplayable(budget)}
-    />
-  )
+export const Success = ({
+  monthlyBudget,
+}: CellSuccessProps<FindBudgetByMonth>) => {
+  return <DataTable columns={columns} data={monthlyBudget} />
 }
diff --git a/web/src/components/MonthlyBudgetsCell/convertData.ts b/web/src/components/MonthlyBudgetsCell/convertData.ts
deleted file mode 100644
index 275da90..0000000
--- a/web/src/components/MonthlyBudgetsCell/convertData.ts
+++ /dev/null
@@ -1,39 +0,0 @@
-import type { FindBudgetByMonth } from 'types/graphql'
-
-import type { MonthlyBudget } from 'src/components/Spreadsheet/columns'
-
-type MonthlyBudgetGQL = FindBudgetByMonth['budget']
-type MonthlyBudgetGQLIntoDisplayable = (
-  budget: MonthlyBudgetGQL
-) => MonthlyBudget[]
-
-// TODO do it on the server side
-export const convertBudgetGQLIntoDisplayable: MonthlyBudgetGQLIntoDisplayable =
-  (budget: MonthlyBudgetGQL) => {
-    const groups = budget.budgetCategoryGroups
-    return groups.map((group) => {
-      const categories = group.budgetCategories
-      const subRows = categories.map((category) => {
-        return {
-          id: category.id,
-          category: category.name,
-          assigned: category.monthlyBudgetPerCategory[0]?.assigned || 0,
-          activity:
-            category.monthlyBudgetPerCategory[0]?.monthlyCategoryActivity
-              .activity || 0,
-          available:
-            category.monthlyBudgetPerCategory[0]?.monthlyCategoryActivity
-              .available || 0,
-        }
-      })
-
-      return {
-        id: group.id,
-        category: group.name,
-        assigned: group.monthlyCategoryGroupActivity[0]?.assigned || 0,
-        activity: group.monthlyCategoryGroupActivity[0]?.activity || 0,
-        available: group.monthlyCategoryGroupActivity[0]?.available || 0,
-        subRows,
-      }
-    })
-  }
diff --git a/web/src/components/Spreadsheet/cells.tsx b/web/src/components/Spreadsheet/cells.tsx
index 8b0c580..0eeaacc 100644
--- a/web/src/components/Spreadsheet/cells.tsx
+++ b/web/src/components/Spreadsheet/cells.tsx
@@ -2,9 +2,12 @@ import { useState, useEffect } from 'react'
 
 import { type Row, type Getter } from '@tanstack/react-table'
 import { ChevronDown, ChevronRight } from 'lucide-react'
+import type { FindBudgetByMonth } from 'types/graphql'
 
+import { useLocation } from '@redwoodjs/router'
 import { useMutation } from '@redwoodjs/web'
 
+import { useAuth } from 'src/auth'
 import { QUERY as FIND_THIS_MONTH_BUDGET } from 'src/components/MonthlyBudgetsCell'
 import { useSelectedMonth, useSelectedYear } from 'src/lib/store'
 
@@ -93,12 +96,12 @@ export const CEditableCurrency = ({
     setValue(initialValue)
   }, [initialValue])
 
+  const userId = useAuth().currentUser?.id
+  const budgetId = useLocation().pathname.split('/').pop()
   const month = useSelectedMonth()
   const year = useSelectedYear()
 
-  const [updateAssignedBudgetForCategory] = useMutation(UPDATE_BUDGET, {
-    refetchQueries: [FIND_THIS_MONTH_BUDGET],
-  })
+  const [updateAssignedBudgetForCategory] = useMutation(UPDATE_BUDGET)
 
   const onBlur = () => {
     setValue(format(value))
@@ -110,6 +113,59 @@ export const CEditableCurrency = ({
           year,
           input: { assigned: convertToFloat(value) },
         },
+        update: (cache) => {
+          const existingData = cache.readQuery<FindBudgetByMonth>({
+            query: FIND_THIS_MONTH_BUDGET,
+            variables: {
+              month,
+              year,
+              budgetId,
+              userId,
+            },
+          })
+
+          const { parent, me } = (existingData?.monthlyBudget || []).reduce(
+            (acc, group) => {
+              if (!acc.parent) {
+                const subRow = group.subRows.find(
+                  (subRow) => subRow.id === row.original.id
+                )
+                if (subRow) {
+                  acc.parent = group
+                  acc.me = subRow
+                }
+              }
+              return acc
+            },
+            { parent: null, me: null }
+          )
+
+          const changes = convertToFloat(value) - me.assigned
+
+          cache.modify({
+            id: cache.identify(me),
+            fields: {
+              assigned(cachedAssigned) {
+                return cachedAssigned + changes
+              },
+              available(cachedAvailable) {
+                return cachedAvailable + changes
+              },
+            },
+          })
+
+          cache.modify({
+            id: cache.identify(parent),
+            fields: {
+              assigned(cachedAssigned) {
+                return cachedAssigned + changes
+              },
+              available(cachedAvailable) {
+                return cachedAvailable + changes
+              },
+            },
+          })
+        },
       })
     }
   }
diff --git a/web/src/components/Spreadsheet/columns.tsx b/web/src/components/Spreadsheet/columns.tsx
index e1ecc5f..1da8851 100644
--- a/web/src/components/Spreadsheet/columns.tsx
+++ b/web/src/components/Spreadsheet/columns.tsx
@@ -12,6 +12,7 @@ import { HExpand, HCheckbox } from './header'
 // This type is used to define the shape of our data.
 // You can use a Zod schema here if you want.
 export type MonthlyBudget = {
+  __typename?: string
   id: string
   category: string
   assigned: number