diff --git a/legacy/app/common/util_amount.c b/legacy/app/common/util_amount.c
index 94b0549..27cfa6c 100644
--- a/legacy/app/common/util_amount.c
+++ b/legacy/app/common/util_amount.c
@@ -1,82 +1,61 @@
-/*
- * util_amount.c - 금액/통화 유틸리티 (plain C)
- */
-#include "acq_util.h"
-
+#include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
-#include <stdio.h>
 
-/* 거래금액 상한 (원). 건당 1억원 */
-#define AMOUNT_MAX  100000000L
+#define AMOUNT_BUF_SIZE 64
 
-long amount_parse(const char *field, int len)
-{
-    long v = 0;
-    int  i;
+typedef struct {
+    long long units;
+    int cents;
+    char currency[4];
+} amount_t;
 
-    if (!field || len <= 0)
-        return -1;
-
-    for (i = 0; i < len; i++) {
-        char c = field[i];
-        if (c == ' ')            /* 선행 공백 허용 */
-            continue;
-        if (!isdigit((unsigned char)c))
-            return -1;
-        v = v * 10 + (c - '0');
+int amount_parse(const char* str, amount_t* out) {
+    if (!str || !out) return -1;
+    long long units = 0;
+    int cents = 0;
+    char currency[4] = "KRW";
+    const char* p = str;
+    while (*p && !isdigit(*p) && *p != '.' && *p != '-') p++;
+    if (sscanf(p, "%lld.%2d", &units, &cents) >= 1) {
+        out->units = units;
+        out->cents = cents;
+        strcpy(out->currency, currency);
+        return 0;
     }
-    return v;
+    return -1;
 }
 
-int amount_format(long amount, char *out, int len)
-{
-    char tmp[32];
-    int  n;
+int amount_format(const amount_t* a, char* buf, size_t len) {
+    if (!a || !buf) return -1;
+    return snprintf(buf, len, "%s %lld.%02d", a->currency, a->units, a->cents);
+}
 
-    if (!out || len <= 0 || amount < 0)
-        return -1;
-
-    n = snprintf(tmp, sizeof(tmp), "%0*ld", len, amount);
-    if (n < 0 || n > len)        /* 폭 초과 = 오버플로우 */
-        return -1;
-
-    memcpy(out, tmp, len);       /* 널 종료 없이 고정폭 복사 */
+int amount_add(const amount_t* a, const amount_t* b, amount_t* out) {
+    if (!a || !b || !out) return -1;
+    long long total_cents = a->units * 100 + a->cents + b->units * 100 + b->cents;
+    out->units = total_cents / 100;
+    out->cents = (int)(total_cents % 100);
+    strcpy(out->currency, a->currency);
     return 0;
 }
 
-void amount_format_won(long amount, char *out, int outlen)
-{
-    char raw[32];
-    int  n, i, j, digits, first;
-
-    if (!out || outlen <= 0)
-        return;
-
-    n = snprintf(raw, sizeof(raw), "%ld", amount);
-    if (n < 0) {
-        out[0] = '\0';
-        return;
-    }
-
-    first = (raw[0] == '-') ? 1 : 0;
-    digits = n - first;
-
-    j = 0;
-    if (first && j < outlen - 1)
-        out[j++] = '-';
-
-    for (i = first; i < n && j < outlen - 1; i++) {
-        int pos = i - first;      /* 0-based 자릿수 위치 */
-        if (pos > 0 && (digits - pos) % 3 == 0)
-            if (j < outlen - 1)
-                out[j++] = ',';
-        out[j++] = raw[i];
-    }
-    out[j] = '\0';
+int amount_subtract(const amount_t* a, const amount_t* b, amount_t* out) {
+    if (!a || !b || !out) return -1;
+    long long total_cents = (a->units * 100 + a->cents) - (b->units * 100 + b->cents);
+    out->units = total_cents / 100;
+    out->cents = (int)(total_cents % 100);
+    if (total_cents < 0) out->cents = -out->cents;
+    strcpy(out->currency, a->currency);
+    return 0;
 }
 
-int amount_is_valid(long amount)
-{
-    return (amount >= 1 && amount <= AMOUNT_MAX) ? 1 : 0;
+int amount_multiply(const amount_t* a, int factor, amount_t* out) {
+    if (!a || !out) return -1;
+    long long total_cents = (a->units * 100 + a->cents) * factor;
+    out->units = total_cents / 100;
+    out->cents = (int)(total_cents % 100);
+    strcpy(out->currency, a->currency);
+    return 0;
 }