diff --git a/apps/as/src/entities/elapr/model/elapr-dmnd-interface.ts b/apps/as/src/entities/elapr/model/elapr-dmnd-interface.ts
index 5d05fd04b..3b0b0d7e5 100644
--- a/apps/as/src/entities/elapr/model/elapr-dmnd-interface.ts
+++ b/apps/as/src/entities/elapr/model/elapr-dmnd-interface.ts
@@ -7,8 +7,8 @@ export interface ElaprDmndSaveRequestDto {
   elaprDocNo: string;
   dmndTtl: string;
   dmndCn: string;
-  elaprCycl?: number;
-  docPrgrsSttsComCd?: string;
+  elaprCycl?: number | null;
+  docPrgrsSttsComCd?: string | null;
   elaprPrgrsSttsList?: ElaprPrgrsSttsSaveRequestDto[];
 }
 
diff --git a/apps/as/src/pages/design-cnstn/lib/design-cnstn-regist-schema.ts b/apps/as/src/pages/design-cnstn/lib/design-cnstn-regist-schema.ts
index d0e4e894f..fbb6c9147 100644
--- a/apps/as/src/pages/design-cnstn/lib/design-cnstn-regist-schema.ts
+++ b/apps/as/src/pages/design-cnstn/lib/design-cnstn-regist-schema.ts
@@ -52,7 +52,7 @@ export function formatTaskSeComCdForApi(taskSeComCd: string[]): string {
   return taskSeComCd.join(",");
 }
 
-export function parseTaskSeComCdFromApi(taskSeComCd?: string): string[] {
+export function parseTaskSeComCdFromApi(taskSeComCd?: string | null): string[] {
   if (!taskSeComCd) return [];
   return taskSeComCd.split(",").filter(Boolean);
 }
diff --git a/apps/as/src/pages/design-cnstn/model/columns.tsx b/apps/as/src/pages/design-cnstn/model/columns.tsx
index 083bd08fe..429c209aa 100644
--- a/apps/as/src/pages/design-cnstn/model/columns.tsx
+++ b/apps/as/src/pages/design-cnstn/model/columns.tsx
@@ -72,7 +72,7 @@ function getBadgeColor(state: BadgeState) {
   }
 }
 
-function formatOptional(value: string | undefined) {
+function formatOptional(value: string | null | undefined) {
   return value?.trim() ? value : "-";
 }
 
diff --git a/apps/as/src/pages/fnrs-cnsltn/lib/fnrs-cnsltn-regist-schema.ts b/apps/as/src/pages/fnrs-cnsltn/lib/fnrs-cnsltn-regist-schema.ts
index b24547422..f0dbd8ad2 100644
--- a/apps/as/src/pages/fnrs-cnsltn/lib/fnrs-cnsltn-regist-schema.ts
+++ b/apps/as/src/pages/fnrs-cnsltn/lib/fnrs-cnsltn-regist-schema.ts
@@ -88,7 +88,7 @@ export function formatTaskSeComCdForApi(taskSeComCd: string[]): string {
   return taskSeComCd.join(",");
 }
 
-export function parseTaskSeComCdFromApi(taskSeComCd?: string): string[] {
+export function parseTaskSeComCdFromApi(taskSeComCd?: string | null): string[] {
   if (!taskSeComCd) return [];
   return taskSeComCd.split(",").filter(Boolean);
 }
diff --git a/apps/as/src/pages/fnrs-cnsltn/model/columns.tsx b/apps/as/src/pages/fnrs-cnsltn/model/columns.tsx
index 2374b0c40..d033b290e 100644
--- a/apps/as/src/pages/fnrs-cnsltn/model/columns.tsx
+++ b/apps/as/src/pages/fnrs-cnsltn/model/columns.tsx
@@ -113,7 +113,7 @@ function getBadgeColor(state: BadgeState) {
   }
 }
 
-function formatOptional(value: string | undefined) {
+function formatOptional(value: string | null | undefined) {
   return value?.trim() ? value : "-";
 }
 
diff --git a/apps/as/src/pages/instl-sncn/lib/instl-sncn-regist-schema.ts b/apps/as/src/pages/instl-sncn/lib/instl-sncn-regist-schema.ts
index 83cd21d3a..c7bd4d77c 100644
--- a/apps/as/src/pages/instl-sncn/lib/instl-sncn-regist-schema.ts
+++ b/apps/as/src/pages/instl-sncn/lib/instl-sncn-regist-schema.ts
@@ -82,7 +82,7 @@ export function formatTaskSeComCdForApi(taskSeComCd: string[]): string {
   return taskSeComCd.join(",");
 }
 
-export function parseTaskSeComCdFromApi(taskSeComCd?: string): string[] {
+export function parseTaskSeComCdFromApi(taskSeComCd?: string | null): string[] {
   if (!taskSeComCd) return [];
   return taskSeComCd.split(",").filter(Boolean);
 }
diff --git a/apps/as/src/pages/instl-sncn/model/columns.tsx b/apps/as/src/pages/instl-sncn/model/columns.tsx
index 11d51de65..f00d05720 100644
--- a/apps/as/src/pages/instl-sncn/model/columns.tsx
+++ b/apps/as/src/pages/instl-sncn/model/columns.tsx
@@ -114,7 +114,7 @@ function getBadgeColor(state: BadgeState) {
   }
 }
 
-function formatOptional(value: string | undefined) {
+function formatOptional(value: string | null | undefined) {
   return value?.trim() ? value : "-";
 }
 
diff --git a/apps/as/src/pages/sewer-bsc-plan/lib/fnrs-cst-form-utils.ts b/apps/as/src/pages/sewer-bsc-plan/lib/fnrs-cst-form-utils.ts
index 57de61985..fde0f5ea4 100644
--- a/apps/as/src/pages/sewer-bsc-plan/lib/fnrs-cst-form-utils.ts
+++ b/apps/as/src/pages/sewer-bsc-plan/lib/fnrs-cst-form-utils.ts
@@ -1,14 +1,14 @@
 import { type CostItemDef, roundAmount } from "@/widgets/pbadms-sprt";
 
-import { type BizCstMatrixItem,getAmt, PLAN_STEPS } from "./biz-cst-matrix-utils";
+import { type BizCstMatrixItem, getAmt, PLAN_STEPS } from "./biz-cst-matrix-utils";
 
 export interface FnrsCstItem {
   planStpNo: number;
-  gvexpAmt?: number;
-  lcexpAmt?: number;
-  orgprBdchgAmt?: number;
-  etcAmt?: number;
-  sumAmt?: number;
+  gvexpAmt?: number | null;
+  lcexpAmt?: number | null;
+  orgprBdchgAmt?: number | null;
+  etcAmt?: number | null;
+  sumAmt?: number | null;
 }
 
 export interface FnrsCstStepRemaining {
@@ -32,10 +32,7 @@ function getBizCstStepTotal(
 
 function sumFnrsCstLeaf(item: FnrsCstItem): number {
   return roundAmount(
-    (item.gvexpAmt ?? 0) +
-      (item.lcexpAmt ?? 0) +
-      (item.orgprBdchgAmt ?? 0) +
-      (item.etcAmt ?? 0),
+    (item.gvexpAmt ?? 0) + (item.lcexpAmt ?? 0) + (item.orgprBdchgAmt ?? 0) + (item.etcAmt ?? 0),
   );
 }
 
diff --git a/apps/as/src/pages/sewer-bsc-plan/ui/previous-plan-lookup-dialog.tsx b/apps/as/src/pages/sewer-bsc-plan/ui/previous-plan-lookup-dialog.tsx
index 0d0d6f4a8..b2c854487 100644
--- a/apps/as/src/pages/sewer-bsc-plan/ui/previous-plan-lookup-dialog.tsx
+++ b/apps/as/src/pages/sewer-bsc-plan/ui/previous-plan-lookup-dialog.tsx
@@ -31,7 +31,7 @@ interface PreviousPlanLookupDialogProps {
   open: boolean;
   onOpenChange: (open: boolean) => void;
   /** 부모 폼 `sewerBscPlan.sido` 표시명 */
-  initialSidoNm?: string;
+  initialSidoNm?: string | null;
   /** 부모 폼 `sewerBscPlan.gugun` 표시명 */
   initialGugunNm?: string | null;
 }
diff --git a/apps/as/src/pages/sewer-bsc-plan/ui/sections/tmplnt-form-section.tsx b/apps/as/src/pages/sewer-bsc-plan/ui/sections/tmplnt-form-section.tsx
index 89b25aee9..51f59d559 100644
--- a/apps/as/src/pages/sewer-bsc-plan/ui/sections/tmplnt-form-section.tsx
+++ b/apps/as/src/pages/sewer-bsc-plan/ui/sections/tmplnt-form-section.tsx
@@ -214,8 +214,8 @@ function TmplntFacilityMatrix({
 interface TmplntFacilityAttachmentsProps {
   facilityIndex: number;
   facilityName?: string;
-  atchFileGroupId?: string;
-  atchFileNm?: string;
+  atchFileGroupId?: string | null;
+  atchFileNm?: string | null;
 }
 
 function TmplntFacilityAttachments({
diff --git a/apps/as/src/shared/model/pbadms-sprt.ts b/apps/as/src/shared/model/pbadms-sprt.ts
index 669e3a234..0d08874d5 100644
--- a/apps/as/src/shared/model/pbadms-sprt.ts
+++ b/apps/as/src/shared/model/pbadms-sprt.ts
@@ -205,14 +205,14 @@ export interface EsntlAtchFileSaveBase {
 export interface SplmntDmndSaveBase {
   splmntDmndSn?: number | null;
   splmntArtclComCd?: string | null;
-  splmntDmndCn?: string;
-  splmntDmndDt?: string;
+  splmntDmndCn?: string | null;
+  splmntDmndDt?: string | null;
   splmntDmndAtchFileGroupId?: string | null;
-  splmntCn?: string;
-  splmntPicNm?: string;
-  splmntCmptnDt?: string;
-  splmntAtchFileGroupId?: string;
-  cmptnYn?: string;
+  splmntCn?: string | null;
+  splmntPicNm?: string | null;
+  splmntCmptnDt?: string | null;
+  splmntAtchFileGroupId?: string | null;
+  cmptnYn?: string | null;
 }
 
 /** 검토의견 저장 공통 필드 (문서번호 제외) */
diff --git a/apps/as/src/widgets/pbadms-sprt/lib/can-edit-pbadms-doc.ts b/apps/as/src/widgets/pbadms-sprt/lib/can-edit-pbadms-doc.ts
index ba626a08c..18efd5c67 100644
--- a/apps/as/src/widgets/pbadms-sprt/lib/can-edit-pbadms-doc.ts
+++ b/apps/as/src/widgets/pbadms-sprt/lib/can-edit-pbadms-doc.ts
@@ -1,8 +1,8 @@
 interface CanEditPbadmsDocParams {
   docSeComCd: string;
-  prgrsSttsComCd: string | undefined;
-  rgtr: string | undefined;
-  loggedInUserUnqId: string | undefined;
+  prgrsSttsComCd?: string | null;
+  rgtr?: string | null;
+  loggedInUserUnqId?: string | null;
 }
 
 function canEditPbadmsDoc({
diff --git a/apps/as/src/widgets/pbadms-sprt/lib/fnrs-shar-form-utils.ts b/apps/as/src/widgets/pbadms-sprt/lib/fnrs-shar-form-utils.ts
index d593d4aee..9f6959bbf 100644
--- a/apps/as/src/widgets/pbadms-sprt/lib/fnrs-shar-form-utils.ts
+++ b/apps/as/src/widgets/pbadms-sprt/lib/fnrs-shar-form-utils.ts
@@ -17,8 +17,8 @@ export interface FnrsSharListItem {
   fnrsSharSeCd: string;
   exstnAmt: number;
   chgRqtAmt: number;
-  ajmtAmt?: number;
-  rmrkCn?: string;
+  ajmtAmt?: number | null;
+  rmrkCn?: string | null;
 }
 
 export type FnrsSharTreeNode = FnrsSharSeMngTreeDto | FnrsSharBizCstTreeDto;
diff --git a/apps/as/src/widgets/pbadms-sprt/ui/splmnt-dmnd-form-section.tsx b/apps/as/src/widgets/pbadms-sprt/ui/splmnt-dmnd-form-section.tsx
index 2738e5c1f..711415a46 100644
--- a/apps/as/src/widgets/pbadms-sprt/ui/splmnt-dmnd-form-section.tsx
+++ b/apps/as/src/widgets/pbadms-sprt/ui/splmnt-dmnd-form-section.tsx
@@ -286,7 +286,15 @@ function SplmntDmndFormSection({ readOnly = false }: SplmntDmndFormSectionProps)
                   </TableCell>
                   <TableCell className="align-top">
                     {isRowReadOnly ? (
-                      <span className="whitespace-pre-wrap">{item.splmntCn || "-"}</span>
+                      <div className="space-y-2">
+                        <div className="whitespace-pre-wrap">{item.splmntCn || "-"}</div>
+                        {item.splmntAtchFileGroupId ? (
+                          <AttachmentDownloadLink
+                            atflCd={item.splmntAtchFileGroupId}
+                            fileName={rowFiles[0]?.fileName}
+                          />
+                        ) : null}
+                      </div>
                     ) : (
                       <Controller
                         control={control}