diff --git a/src/app/api/timesheets/utils.ts b/src/app/api/timesheets/utils.ts
index c305e26..22d31ce 100644
--- a/src/app/api/timesheets/utils.ts
+++ b/src/app/api/timesheets/utils.ts
@@ -1,36 +1,49 @@
 import { LeaveEntry, TimeEntry } from "./actions";
 
+export type TimeEntryError = {
+  [field in keyof TimeEntry]?: string;
+};
+
 /**
  * @param entry - the time entry
  * @returns the field where there is an error, or an empty string if there is none
  */
-export const isValidTimeEntry = (entry: Partial<TimeEntry>): string => {
+export const validateTimeEntry = (
+  entry: Partial<TimeEntry>,
+  isHoliday: boolean,
+): TimeEntryError | undefined => {
   // Test for errors
-  let error: keyof TimeEntry | "" = "";
+  const error: TimeEntryError = {};
 
   // Either normal or other hours need to be inputted
   if (!entry.inputHours && !entry.otHours) {
-    error = "inputHours";
+    error[isHoliday ? "otHours" : "inputHours"] = "Required";
+  } else if (entry.inputHours && isHoliday) {
+    error.inputHours = "Cannot input normal hours for holidays";
   } else if (entry.inputHours && entry.inputHours <= 0) {
-    error = "inputHours";
+    error.inputHours =
+      "Input hours should be between 0 and {{DAILY_NORMAL_MAX_HOURS}}";
+  } else if (entry.inputHours && entry.inputHours > DAILY_NORMAL_MAX_HOURS) {
+    error.inputHours =
+      "Input hours should be between 0 and {{DAILY_NORMAL_MAX_HOURS}}";
   } else if (entry.otHours && entry.otHours <= 0) {
-    error = "otHours";
+    error.otHours = "Hours should be bigger than 0";
   }
 
   // If there is a project id, there should also be taskGroupId, taskId, inputHours
   if (entry.projectId) {
     if (!entry.taskGroupId) {
-      error = "taskGroupId";
+      error.taskGroupId = "Required";
     } else if (!entry.taskId) {
-      error = "taskId";
+      error.taskId = "Required";
     }
   } else {
     if (!entry.remark) {
-      error = "remark";
+      error.remark = "Required for non-billable tasks";
     }
   }
 
-  return error;
+  return Object.keys(error).length > 0 ? error : undefined;
 };
 
 export const isValidLeaveEntry = (entry: Partial<LeaveEntry>): string => {
@@ -45,5 +58,6 @@ export const isValidLeaveEntry = (entry: Partial<LeaveEntry>): string => {
   return error;
 };
 
+export const DAILY_NORMAL_MAX_HOURS = 8;
 export const LEAVE_DAILY_MAX_HOURS = 8;
 export const TIMESHEET_DAILY_MAX_HOURS = 20;
diff --git a/src/components/DateHoursTable/DateHoursTable.tsx b/src/components/DateHoursTable/DateHoursTable.tsx
index 7a659d0..8328bd9 100644
--- a/src/components/DateHoursTable/DateHoursTable.tsx
+++ b/src/components/DateHoursTable/DateHoursTable.tsx
@@ -33,7 +33,7 @@ interface Props<EntryTableProps = object> {
   timesheetEntries: RecordTimesheetInput;
   companyHolidays: HolidaysResult[];
   EntryTableComponent: React.FunctionComponent<
-    EntryTableProps & { day: string }
+    EntryTableProps & { day: string; isHoliday: boolean }
   >;
   entryTableProps: EntryTableProps;
 }
@@ -86,14 +86,14 @@ function DayRow<EntryTableProps>({
   timesheetEntries,
   entryTableProps,
   EntryTableComponent,
-  companyHolidays
+  companyHolidays,
 }: {
   day: string;
   companyHolidays: HolidaysResult[];
   leaveEntries: RecordLeaveInput;
   timesheetEntries: RecordTimesheetInput;
   EntryTableComponent: React.FunctionComponent<
-    EntryTableProps & { day: string }
+    EntryTableProps & { day: string; isHoliday: boolean }
   >;
   entryTableProps: EntryTableProps;
 }) {
@@ -200,7 +200,15 @@ function DayRow<EntryTableProps>({
           colSpan={5}
         >
           <Collapse in={open} timeout="auto" unmountOnExit>
-            <Box>{<EntryTableComponent day={day} {...entryTableProps} />}</Box>
+            <Box>
+              {
+                <EntryTableComponent
+                  day={day}
+                  isHoliday={Boolean(isHoliday)}
+                  {...entryTableProps}
+                />
+              }
+            </Box>
           </Collapse>
         </TableCell>
       </TableRow>
diff --git a/src/components/LeaveTable/LeaveEditModal.tsx b/src/components/LeaveTable/LeaveEditModal.tsx
index e5c7d83..2434e7a 100644
--- a/src/components/LeaveTable/LeaveEditModal.tsx
+++ b/src/components/LeaveTable/LeaveEditModal.tsx
@@ -1,5 +1,6 @@
 import { LeaveType } from "@/app/api/timesheets";
 import { LeaveEntry } from "@/app/api/timesheets/actions";
+import { LEAVE_DAILY_MAX_HOURS } from "@/app/api/timesheets/utils";
 import { roundToNearestQuarter } from "@/app/utils/manhourUtils";
 import { Check, Delete } from "@mui/icons-material";
 import {
@@ -100,7 +101,7 @@ const LeaveEditModal: React.FC<Props> = ({
           fullWidth
           {...register("inputHours", {
             setValueAs: (value) => roundToNearestQuarter(parseFloat(value)),
-            validate: (value) => value > 0,
+            validate: (value) => 0 < value && value <= LEAVE_DAILY_MAX_HOURS,
           })}
           error={Boolean(formState.errors.inputHours)}
         />
diff --git a/src/components/LeaveTable/LeaveEntryTable.tsx b/src/components/LeaveTable/LeaveEntryTable.tsx
index d612112..d00d50e 100644
--- a/src/components/LeaveTable/LeaveEntryTable.tsx
+++ b/src/components/LeaveTable/LeaveEntryTable.tsx
@@ -28,6 +28,7 @@ dayjs.extend(isBetween);
 
 interface Props {
   day: string;
+  isHoliday: boolean;
   leaveTypes: LeaveType[];
 }
 
diff --git a/src/components/TimesheetTable/EntryInputTable.tsx b/src/components/TimesheetTable/EntryInputTable.tsx
index effd88b..bccd9df 100644
--- a/src/components/TimesheetTable/EntryInputTable.tsx
+++ b/src/components/TimesheetTable/EntryInputTable.tsx
@@ -1,9 +1,11 @@
 import { Add, Check, Close, Delete } from "@mui/icons-material";
-import { Box, Button, Typography } from "@mui/material";
+import { Box, Button, Tooltip, Typography } from "@mui/material";
 import {
   FooterPropsOverrides,
   GridActionsCellItem,
+  GridCellParams,
   GridColDef,
+  GridEditInputCell,
   GridEventListener,
   GridRenderEditCellParams,
   GridRowId,
@@ -27,13 +29,18 @@ import isBetween from "dayjs/plugin/isBetween";
 import ProjectSelect from "./ProjectSelect";
 import TaskGroupSelect from "./TaskGroupSelect";
 import TaskSelect from "./TaskSelect";
-import { isValidTimeEntry } from "@/app/api/timesheets/utils";
+import {
+  DAILY_NORMAL_MAX_HOURS,
+  TimeEntryError,
+  validateTimeEntry,
+} from "@/app/api/timesheets/utils";
 import { roundToNearestQuarter } from "@/app/utils/manhourUtils";
 
 dayjs.extend(isBetween);
 
 interface Props {
   day: string;
+  isHoliday: boolean;
   allProjects: ProjectWithTasks[];
   assignedProjects: AssignedProject[];
 }
@@ -41,7 +48,7 @@ interface Props {
 export type TimeEntryRow = Partial<
   TimeEntry & {
     _isNew: boolean;
-    _error: string;
+    _error: TimeEntryError;
     isPlanned?: boolean;
   }
 >;
@@ -50,6 +57,7 @@ const EntryInputTable: React.FC<Props> = ({
   day,
   allProjects,
   assignedProjects,
+  isHoliday,
 }) => {
   const { t } = useTranslation("home");
   const taskGroupsByProject = useMemo(() => {
@@ -105,7 +113,7 @@ const EntryInputTable: React.FC<Props> = ({
         "",
       ) as TimeEntryRow;
 
-      const error = isValidTimeEntry(row);
+      const error = validateTimeEntry(row, isHoliday);
 
       // Test for warnings
       let isPlanned;
@@ -124,7 +132,7 @@ const EntryInputTable: React.FC<Props> = ({
       apiRef.current.updateRows([{ id, _error: error, isPlanned }]);
       return !error;
     },
-    [apiRef, day, milestonesByProject],
+    [apiRef, day, isHoliday, milestonesByProject],
   );
 
   const handleCancel = useCallback(
@@ -309,6 +317,18 @@ const EntryInputTable: React.FC<Props> = ({
         width: 100,
         editable: true,
         type: "number",
+        renderEditCell(params: GridRenderEditCellParams<TimeEntryRow>) {
+          const errorMessage =
+            params.row._error?.[params.field as keyof TimeEntry];
+          const content = <GridEditInputCell {...params} />;
+          return errorMessage ? (
+            <Tooltip title={t(errorMessage, { DAILY_NORMAL_MAX_HOURS })}>
+              {content}
+            </Tooltip>
+          ) : (
+            content
+          );
+        },
         valueParser(value) {
           return value ? roundToNearestQuarter(value) : value;
         },
@@ -322,6 +342,16 @@ const EntryInputTable: React.FC<Props> = ({
         width: 150,
         editable: true,
         type: "number",
+        renderEditCell(params: GridRenderEditCellParams<TimeEntryRow>) {
+          const errorMessage =
+            params.row._error?.[params.field as keyof TimeEntry];
+          const content = <GridEditInputCell {...params} />;
+          return errorMessage ? (
+            <Tooltip title={t(errorMessage)}>{content}</Tooltip>
+          ) : (
+            content
+          );
+        },
         valueParser(value) {
           return value ? roundToNearestQuarter(value) : value;
         },
@@ -335,6 +365,16 @@ const EntryInputTable: React.FC<Props> = ({
         sortable: false,
         flex: 1,
         editable: true,
+        renderEditCell(params: GridRenderEditCellParams<TimeEntryRow>) {
+          const errorMessage =
+            params.row._error?.[params.field as keyof TimeEntry];
+          const content = <GridEditInputCell {...params} />;
+          return errorMessage ? (
+            <Tooltip title={t(errorMessage)}>{content}</Tooltip>
+          ) : (
+            content
+          );
+        },
       },
     ],
     [
@@ -406,9 +446,9 @@ const EntryInputTable: React.FC<Props> = ({
       onRowEditStop={handleEditStop}
       processRowUpdate={processRowUpdate}
       columns={columns}
-      getCellClassName={(params) => {
+      getCellClassName={(params: GridCellParams<TimeEntryRow>) => {
         let classname = "";
-        if (params.row._error === params.field) {
+        if (params.row._error?.[params.field as keyof TimeEntry]) {
           classname = "hasError";
         } else if (
           params.field === "taskGroupId" &&
diff --git a/src/components/TimesheetTable/MobileTimesheetEntry.tsx b/src/components/TimesheetTable/MobileTimesheetEntry.tsx
index 174f22b..96669da 100644
--- a/src/components/TimesheetTable/MobileTimesheetEntry.tsx
+++ b/src/components/TimesheetTable/MobileTimesheetEntry.tsx
@@ -158,6 +158,7 @@ const MobileTimesheetEntry: React.FC<Props> = ({
           open={editModalOpen}
           onClose={closeEditModal}
           onSave={onSaveEntry}
+          isHoliday={Boolean(isHoliday)}
           {...editModalProps}
         />
       </Box>
diff --git a/src/components/TimesheetTable/TimesheetEditModal.tsx b/src/components/TimesheetTable/TimesheetEditModal.tsx
index 7a24f25..6fe33d5 100644
--- a/src/components/TimesheetTable/TimesheetEditModal.tsx
+++ b/src/components/TimesheetTable/TimesheetEditModal.tsx
@@ -23,6 +23,7 @@ import { TaskGroup } from "@/app/api/tasks";
 import uniqBy from "lodash/uniqBy";
 import { roundToNearestQuarter } from "@/app/utils/manhourUtils";
 import { shortDateFormatter } from "@/app/utils/formatUtil";
+import { DAILY_NORMAL_MAX_HOURS } from "@/app/api/timesheets/utils";
 
 export interface Props extends Omit<ModalProps, "children"> {
   onSave: (timeEntry: TimeEntry, recordDate?: string) => Promise<void>;
@@ -32,6 +33,7 @@ export interface Props extends Omit<ModalProps, "children"> {
   assignedProjects: AssignedProject[];
   modalSx?: SxProps;
   recordDate?: string;
+  isHoliday?: boolean;
 }
 
 const modalSx: SxProps = {
@@ -56,6 +58,7 @@ const TimesheetEditModal: React.FC<Props> = ({
   assignedProjects,
   modalSx: mSx,
   recordDate,
+  isHoliday,
 }) => {
   const {
     t,
@@ -212,10 +215,26 @@ const TimesheetEditModal: React.FC<Props> = ({
           fullWidth
           {...register("inputHours", {
             setValueAs: (value) => roundToNearestQuarter(parseFloat(value)),
-            validate: (value) =>
-              value ? value > 0 : Boolean(value || otHours),
+            validate: (value) => {
+              if (value) {
+                if (isHoliday) {
+                  return t("Cannot input normal hours for holidays");
+                }
+
+                return (
+                  (0 < value && value <= DAILY_NORMAL_MAX_HOURS) ||
+                  t(
+                    "Input hours should be between 0 and {{DAILY_NORMAL_MAX_HOURS}}",
+                    { DAILY_NORMAL_MAX_HOURS },
+                  )
+                );
+              } else {
+                return Boolean(value || otHours) || t("Required");
+              }
+            },
           })}
           error={Boolean(formState.errors.inputHours)}
+          helperText={formState.errors.inputHours?.message}
         />
         <TextField
           type="number"
@@ -234,8 +253,11 @@ const TimesheetEditModal: React.FC<Props> = ({
           rows={2}
           error={Boolean(formState.errors.remark)}
           {...register("remark", {
-            validate: (value) => Boolean(projectId || value),
+            validate: (value) =>
+              Boolean(projectId || value) ||
+              t("Required for non-billable tasks"),
           })}
+          helperText={formState.errors.remark?.message}
         />
         <Box display="flex" justifyContent="flex-end" gap={1}>
           {onDelete && (