diff --git a/src/components/CreateProject/BulkAddPaymentModal.tsx b/src/components/CreateProject/BulkAddPaymentModal.tsx
new file mode 100644
index 0000000..6555dc8
--- /dev/null
+++ b/src/components/CreateProject/BulkAddPaymentModal.tsx
@@ -0,0 +1,317 @@
+import { Check, ExpandMore } from "@mui/icons-material";
+import {
+  Accordion,
+  AccordionDetails,
+  AccordionSummary,
+  Alert,
+  Box,
+  Button,
+  Divider,
+  FormControl,
+  FormHelperText,
+  InputLabel,
+  MenuItem,
+  Modal,
+  ModalProps,
+  Paper,
+  Select,
+  SxProps,
+  TextField,
+  Typography,
+} from "@mui/material";
+import React, { useCallback, useMemo } from "react";
+import { Controller, useForm } from "react-hook-form";
+import { useTranslation } from "react-i18next";
+import {
+  INPUT_DATE_FORMAT,
+  moneyFormatter,
+  OUTPUT_DATE_FORMAT,
+} from "@/app/utils/formatUtil";
+import { PaymentInputs } from "@/app/api/projects/actions";
+import dayjs from "dayjs";
+import { DatePicker } from "@mui/x-date-pickers";
+
+export interface BulkAddPaymentForm {
+  numberOfEntries: number;
+  amountToDivide: number;
+  dateType: "monthly" | "weekly" | "fixed";
+  dateReference?: dayjs.Dayjs;
+  description: string;
+}
+
+export interface Props extends Omit<ModalProps, "children"> {
+  onSave: (payments: PaymentInputs[]) => Promise<void>;
+  modalSx?: SxProps;
+}
+
+const modalSx: SxProps = {
+  position: "absolute",
+  top: "50%",
+  left: "50%",
+  transform: "translate(-50%, -50%)",
+  width: "90%",
+  maxWidth: "sm",
+  maxHeight: "90%",
+  padding: 3,
+  display: "flex",
+  flexDirection: "column",
+  gap: 2,
+};
+
+let idOffset = Date.now();
+const getID = () => {
+  return ++idOffset;
+};
+
+const BulkAddPaymentModal: React.FC<Props> = ({
+  onSave,
+  open,
+  onClose,
+  modalSx: mSx,
+}) => {
+  const { t } = useTranslation();
+
+  const { register, reset, trigger, formState, watch, control } =
+    useForm<BulkAddPaymentForm>({
+      defaultValues: { dateType: "monthly", dateReference: dayjs() },
+    });
+
+  const formValues = watch();
+
+  const newPayments = useMemo<PaymentInputs[]>(() => {
+    const {
+      numberOfEntries,
+      amountToDivide,
+      dateType,
+      dateReference = dayjs(),
+      description,
+    } = formValues;
+
+    if (numberOfEntries > 0 && amountToDivide && description) {
+      const dividedAmount = amountToDivide / numberOfEntries;
+      return Array(numberOfEntries)
+        .fill(undefined)
+        .map((_, index) => {
+          const date =
+            dateType === "fixed"
+              ? dateReference
+              : dateReference.add(
+                  index,
+                  dateType === "monthly" ? "month" : "week",
+                );
+
+          return {
+            id: getID(),
+            amount: dividedAmount,
+            description: replaceTemplateString(description, {
+              "{index}": (index + 1).toString(),
+              "{date}": date.format(OUTPUT_DATE_FORMAT),
+            }),
+            date: date.format(INPUT_DATE_FORMAT),
+          };
+        });
+    } else {
+      return [];
+    }
+  }, [formValues]);
+
+  const saveHandler = useCallback(async () => {
+    const valid = await trigger();
+    if (valid) {
+      onSave(newPayments);
+      reset();
+    }
+  }, [trigger, onSave, reset, newPayments]);
+
+  const closeHandler = useCallback<NonNullable<ModalProps["onClose"]>>(
+    (...args) => {
+      onClose?.(...args);
+      reset();
+    },
+    [onClose, reset],
+  );
+
+  return (
+    <Modal open={open} onClose={closeHandler}>
+      <Paper sx={{ ...modalSx, ...mSx }}>
+        <TextField
+          type="number"
+          label={t("Total amount to divide")}
+          fullWidth
+          {...register("amountToDivide", {
+            valueAsNumber: true,
+            required: t("Required"),
+          })}
+          error={Boolean(formState.errors.amountToDivide)}
+          helperText={
+            formState.errors.amountToDivide?.message ||
+            t(
+              "The inputted amount will be evenly divided by the inputted number of payments",
+            )
+          }
+        />
+        <TextField
+          type="number"
+          label={t("Number of payments")}
+          fullWidth
+          {...register("numberOfEntries", {
+            valueAsNumber: true,
+            required: t("Required"),
+          })}
+          error={Boolean(formState.errors.numberOfEntries)}
+          helperText={formState.errors.numberOfEntries?.message}
+        />
+        <FormControl fullWidth error={Boolean(formState.errors.dateType)}>
+          <InputLabel shrink>{t("Default Date Type")}</InputLabel>
+          <Controller
+            control={control}
+            name="dateType"
+            render={({ field }) => (
+              <Select
+                label={t("Date type")}
+                {...field}
+                error={Boolean(formState.errors.dateType)}
+              >
+                <MenuItem value="monthly">{t("Monthly from")}</MenuItem>
+                <MenuItem value="weekly">{t("Weekly from")}</MenuItem>
+                <MenuItem value="fixed">{t("Fixed")}</MenuItem>
+              </Select>
+            )}
+            rules={{
+              required: t("Required"),
+            }}
+          />
+          <FormHelperText>
+            {"The type of date to use for each payment entry."}
+          </FormHelperText>
+        </FormControl>
+        <FormControl fullWidth error={Boolean(formState.errors.dateReference)}>
+          <Controller
+            control={control}
+            name="dateReference"
+            render={({ field }) => (
+              <DatePicker
+                label={t("Date reference")}
+                format={OUTPUT_DATE_FORMAT}
+                {...field}
+              />
+            )}
+            rules={{
+              required: t("Required"),
+            }}
+          />
+          <FormHelperText>
+            {
+              "The reference date for calculating the date for each payment entry."
+            }
+          </FormHelperText>
+        </FormControl>
+        <TextField
+          label={t("Payment description")}
+          fullWidth
+          multiline
+          rows={2}
+          error={Boolean(formState.errors.description)}
+          {...register("description", {
+            required: t("Required"),
+          })}
+          helperText={
+            formState.errors.description?.message ||
+            t(
+              'The description to be added to each payment entry. You can use {date} to reference the generated date and {index} to reference the payment entry index. For example, "Payment {index} ({date})" will create entries with "Payment 1 (YYYY/MM/DD)", "Payment 2 (YYYY/MM/DD)"..., and so on.',
+            )
+          }
+        />
+        <Accordion variant="outlined" sx={{ overflowY: "scroll" }}>
+          <AccordionSummary expandIcon={<ExpandMore />}>
+            <Typography variant="subtitle2">
+              {t("Milestone payments preview")}
+            </Typography>
+          </AccordionSummary>
+          <AccordionDetails>
+            {newPayments.length > 0 ? (
+              <PaymentSummary paymentInputs={newPayments} />
+            ) : (
+              <Alert severity="warning">
+                {t(
+                  "Please input the amount to divde, the number of payments, and the description.",
+                )}
+              </Alert>
+            )}
+          </AccordionDetails>
+        </Accordion>
+        <Box display="flex" justifyContent="flex-end">
+          <Button
+            variant="contained"
+            startIcon={<Check />}
+            onClick={saveHandler}
+          >
+            {t("Save")}
+          </Button>
+        </Box>
+      </Paper>
+    </Modal>
+  );
+};
+
+const PaymentSummary: React.FC<{ paymentInputs: PaymentInputs[] }> = ({
+  paymentInputs,
+}) => {
+  const { t } = useTranslation();
+
+  return (
+    <Box
+      sx={{
+        display: "flex",
+        flexDirection: "column",
+        gap: 2,
+      }}
+    >
+      {paymentInputs.map(({ id, date, description, amount }, index) => {
+        return (
+          <Box key={`${index}-${id}`}>
+            <Box marginBlockEnd={1}>
+              <Typography variant="body2" component="div" fontWeight="bold">
+                {t("Description")}
+              </Typography>
+              <Typography component="p">{description}</Typography>
+            </Box>
+            <Box display="flex" gap={2} justifyContent="space-between">
+              <Box>
+                <Typography variant="body2" component="div" fontWeight="bold">
+                  {t("Date")}
+                </Typography>
+                <Typography component="p">{date}</Typography>
+              </Box>
+              <Box>
+                <Typography variant="body2" component="div" fontWeight="bold">
+                  {t("Amount")}
+                </Typography>
+                <Typography component="p">
+                  {moneyFormatter.format(amount)}
+                </Typography>
+              </Box>
+            </Box>
+            {index !== paymentInputs.length - 1 && (
+              <Divider sx={{ marginBlockStart: 2 }} />
+            )}
+          </Box>
+        );
+      })}
+    </Box>
+  );
+};
+
+const replaceTemplateString = (
+  template: string,
+  replacements: { [key: string]: string },
+): string => {
+  let returnString = template;
+  Object.entries(replacements).forEach(([key, replacement]) => {
+    returnString = returnString.replaceAll(key, replacement);
+  });
+
+  return returnString;
+};
+
+export default BulkAddPaymentModal;
diff --git a/src/components/CreateProject/MilestoneSection.tsx b/src/components/CreateProject/MilestoneSection.tsx
index de810b6..0275189 100644
--- a/src/components/CreateProject/MilestoneSection.tsx
+++ b/src/components/CreateProject/MilestoneSection.tsx
@@ -21,6 +21,7 @@ import {
   useGridApiRef,
   GridRowModel,
   GridRenderEditCellParams,
+  GridCellParams,
 } from "@mui/x-data-grid";
 import { LocalizationProvider, DatePicker } from "@mui/x-date-pickers";
 import { AdapterDayjs } from "@mui/x-date-pickers/AdapterDayjs";
@@ -36,12 +37,33 @@ import {
   moneyFormatter,
 } from "@/app/utils/formatUtil";
 import isDate from "lodash/isDate";
+import BulkAddPaymentModal from "./BulkAddPaymentModal";
 
 interface Props {
   taskGroupId: TaskGroup["id"];
 }
 
-type PaymentRow = Partial<PaymentInputs & { _isNew: boolean; _error: string }>;
+type PaymentRowError = keyof PaymentInputs;
+
+type PaymentRow = Partial<
+  PaymentInputs & { _isNew: boolean; _errors: Set<string> }
+>;
+
+class ProcessRowUpdateError extends Error {
+  public readonly rowId: GridRowId;
+  public readonly errors: Set<PaymentRowError> | undefined;
+  constructor(
+    rowId: GridRowId,
+    message?: string,
+    errors?: Set<PaymentRowError>,
+  ) {
+    super(message);
+    this.rowId = rowId;
+    this.errors = errors;
+
+    Object.setPrototypeOf(this, ProcessRowUpdateError.prototype);
+  }
+}
 
 const MilestoneSection: React.FC<Props> = ({ taskGroupId }) => {
   const {
@@ -72,23 +94,18 @@ const MilestoneSection: React.FC<Props> = ({ taskGroupId }) => {
     }));
   }, [payments]);
 
-  const validateRow = useCallback(
-    (id: GridRowId) => {
-      const row = apiRef.current.getRowWithUpdatedValues(id, "") as PaymentRow;
-      let error: keyof PaymentInputs | "" = "";
-      if (!row.description) {
-        error = "description";
-      } else if (!(isDate(row.date) && row.date.getTime())) {
-        error = "date";
-      } else if (!(row.amount && row.amount >= 0)) {
-        error = "amount";
-      }
+  const validateRow = useCallback((row: PaymentRow) => {
+    const errors = new Set<PaymentRowError>();
+    if (!row.description) {
+      errors.add("description");
+    } else if (!(isDate(row.date) && row.date.getTime())) {
+      errors.add("date");
+    } else if (!(row.amount && row.amount >= 0)) {
+      errors.add("amount");
+    }
 
-      apiRef.current.updateRows([{ id, _error: error }]);
-      return !error;
-    },
-    [apiRef],
-  );
+    return errors;
+  }, []);
 
   const handleCancel = useCallback(
     (id: GridRowId) => () => {
@@ -113,30 +130,45 @@ const MilestoneSection: React.FC<Props> = ({ taskGroupId }) => {
 
   const handleSave = useCallback(
     (id: GridRowId) => () => {
-      if (validateRow(id)) {
-        setRowModesModel((model) => ({
-          ...model,
-          [id]: { mode: GridRowModes.View },
-        }));
-      }
+      setRowModesModel((model) => ({
+        ...model,
+        [id]: { mode: GridRowModes.View },
+      }));
     },
-    [validateRow],
+    [],
   );
 
-  const handleEditStop = useCallback<GridEventListener<"rowEditStop">>(
-    (params, event) => {
-      if (!validateRow(params.id)) {
-        event.defaultMuiPrevented = true;
+  const processRowUpdate = useCallback(
+    (newRow: GridRowModel<PaymentRow>) => {
+      const errors = validateRow(newRow);
+      if (errors.size > 0) {
+        throw new ProcessRowUpdateError(newRow.id!, "validation error", errors);
       }
+
+      // eslint-disable-next-line @typescript-eslint/no-unused-vars
+      const { _isNew, _errors, ...updatedRow } = newRow;
+      setPayments((ps) =>
+        ps.map((p) => (p.id === updatedRow.id ? updatedRow : p)),
+      );
+      return updatedRow;
     },
     [validateRow],
   );
 
-  const processRowUpdate = useCallback((newRow: GridRowModel) => {
-    const updatedRow = { ...newRow, _isNew: false };
-    setPayments((ps) => ps.map((p) => (p.id === newRow.id ? updatedRow : p)));
-    return updatedRow;
-  }, []);
+  const onProcessRowUpdateError = useCallback(
+    (updateError: ProcessRowUpdateError) => {
+      const errors = updateError.errors;
+      const rowId = updateError.rowId;
+
+      apiRef.current.updateRows([
+        {
+          id: rowId,
+          _errors: errors,
+        },
+      ]);
+    },
+    [apiRef],
+  );
 
   const columns = useMemo<GridColDef[]>(
     () => [
@@ -229,7 +261,7 @@ const MilestoneSection: React.FC<Props> = ({ taskGroupId }) => {
       [taskGroupId]: {
         ...milestones[taskGroupId],
         payments: payments
-          .filter((p) => !p._isNew && !p._error)
+          .filter((p) => !p._isNew && !p._errors)
           .map((p) => ({
             description: p.description!,
             id: p.id!,
@@ -240,15 +272,38 @@ const MilestoneSection: React.FC<Props> = ({ taskGroupId }) => {
     });
   }, [getValues, payments, setValue, taskGroupId]);
 
+  // Bulk add modal related
+  const [bulkAddModalOpen, setBulkAddModalOpen] = useState(false);
+  const closeBulkAddModal = useCallback(() => {
+    setBulkAddModalOpen(false);
+  }, []);
+  const openBulkAddModal = useCallback(() => {
+    setBulkAddModalOpen(true);
+  }, []);
+  const onBulkAddSave = useCallback(async (entries: PaymentInputs[]) => {
+    setPayments((currentPayments) => [...currentPayments, ...entries]);
+    setBulkAddModalOpen(false);
+  }, []);
+
   const footer = (
-    <Button
-      variant="outlined"
-      startIcon={<Add />}
-      onClick={addRow}
-      size="small"
-    >
-      {t("Add Payment Milestone")}
-    </Button>
+    <Box display="flex" gap={2} alignItems="center">
+      <Button
+        variant="outlined"
+        startIcon={<Add />}
+        onClick={addRow}
+        size="small"
+      >
+        {t("Add Payment Milestone")}
+      </Button>
+      <Button
+        variant="outlined"
+        startIcon={<Add />}
+        onClick={openBulkAddModal}
+        size="small"
+      >
+        {t("Bulk Add Payment Milestones")}
+      </Button>
+    </Box>
   );
 
   const startDate = getValues("milestones")[taskGroupId]?.startDate;
@@ -345,11 +400,11 @@ const MilestoneSection: React.FC<Props> = ({ taskGroupId }) => {
             rows={payments}
             rowModesModel={rowModesModel}
             onRowModesModelChange={setRowModesModel}
-            onRowEditStop={handleEditStop}
             processRowUpdate={processRowUpdate}
+            onProcessRowUpdateError={onProcessRowUpdateError}
             columns={columns}
-            getCellClassName={(params) => {
-              return params.row._error === params.field ? "hasError" : "";
+            getCellClassName={(params: GridCellParams<PaymentRow>) => {
+              return params.row._errors?.has(params.field) ? "hasError" : "";
             }}
             slots={{
               footer: FooterToolbar,
@@ -361,6 +416,11 @@ const MilestoneSection: React.FC<Props> = ({ taskGroupId }) => {
           />
         </Box>
       </Stack>
+      <BulkAddPaymentModal
+        onSave={onBulkAddSave}
+        open={bulkAddModalOpen}
+        onClose={closeBulkAddModal}
+      />
     </LocalizationProvider>
   );
 };