diff --git a/frontend/app/api/pools/deposit/route.ts b/frontend/app/api/pools/deposit/route.ts
index 4fe425d..651c66c 100644
--- a/frontend/app/api/pools/deposit/route.ts
+++ b/frontend/app/api/pools/deposit/route.ts
@@ -1,6 +1,7 @@
 import { NextRequest, NextResponse } from "next/server"
 import { supabase } from "@/lib/supabase"
 import { writeLimiter } from "@/lib/rate-limit"
+import { normalizeDecimals, humanToBaseUnits, trimHumanAmount } from "@/lib/deposit-token"
 
 const HORIZON_URL =
   process.env.NEXT_PUBLIC_STELLAR_HORIZON_URL || "https://horizon-testnet.stellar.org"
@@ -10,12 +11,20 @@ const HORIZON_URL =
  * complete in Supabase. Prevents off-chain activity rows for deposits that
  * never landed on-chain (e.g. lost confirmations, dropped transactions).
  *
- * POST { poolId, userAddress, txHash, amount? }
+ * POST { poolId, userAddress, txHash, amount?, tokenSymbol?, tokenDecimals? }
  *  - 200 { verified: true } — tx confirmed on-chain (and logged, unless the
  *    hash was already recorded).
  *  - 200 { verified: true, alreadyLogged: true } — previously recorded.
  *  - 422 { verified: false } — tx not found on Horizon or failed on-chain.
  *  - 502 — Horizon unreachable (caller should not mark the deposit complete).
+ *
+ * Multi-token (SEP-41) support: when `tokenSymbol`/`tokenDecimals` are
+ * supplied, the activity row records a `token_amount` (the human deposit
+ * amount denominated in that token) alongside the existing numeric `amount`.
+ * `tokenDecimals` defaults to 7 (native XLM / SAC-wrapped assets); callers
+ * pass a different value for custom tokens. `tokenAmount` is interpreted as a
+ * human amount and converted to base units only for validation — the stored
+ * value stays in human units for display consistency with `token_amount`.
  */
 export async function POST(req: NextRequest) {
   try {
@@ -23,7 +32,7 @@ export async function POST(req: NextRequest) {
     if (limited) return limited
 
     const body = await req.json()
-    const { poolId, userAddress, txHash, amount } = body
+    const { poolId, userAddress, txHash, amount, tokenSymbol, tokenDecimals, tokenAmount } = body
 
     if (!poolId || !userAddress || !txHash) {
       return NextResponse.json(
@@ -77,15 +86,42 @@ export async function POST(req: NextRequest) {
       return NextResponse.json({ verified: true, alreadyLogged: true })
     }
 
-    // 3. Mark the deposit complete in Supabase.
+    // 3. Resolve the per-token amount so the activity row can be broken out
+    //    by currency (issue #255). `tokenAmount` is a human number; we keep
+    //    it in human units for `token_amount`, but validate it converts to a
+    //    whole number of base units at the given decimals (rejecting values
+    //    with more precision than the asset supports).
+    const decimals = normalizeDecimals(tokenDecimals)
+    const tokenAmountHuman =
+      tokenAmount !== undefined && tokenAmount !== null
+        ? trimHumanAmount(String(tokenAmount))
+        : undefined
+    let tokenBaseUnits: bigint | null = null
+    if (tokenAmountHuman !== undefined) {
+      tokenBaseUnits = humanToBaseUnits(tokenAmountHuman, decimals)
+      if (tokenBaseUnits === null) {
+        return NextResponse.json(
+          {
+            error: `tokenAmount has more precision than ${tokenSymbol ?? "asset"} supports (max ${decimals} decimals)`,
+          },
+          { status: 400 }
+        )
+      }
+    }
+
+    // 4. Mark the deposit complete in Supabase.
     const { error } = await supabase.from("pool_activity").insert([
       {
         pool_id: poolId,
         activity_type: "deposit",
         user_address: userAddress.toLowerCase(),
         amount: typeof amount === "number" ? amount : null,
+        token_amount: tokenAmountHuman !== undefined ? Number(tokenAmountHuman) : null,
         tx_hash: txHash,
-        description: "Deposit transaction",
+        description:
+          tokenSymbol && tokenSymbol !== "XLM"
+            ? `Deposit transaction (${tokenSymbol})`
+            : "Deposit transaction",
       },
     ])
 
diff --git a/frontend/components/group/group-actions.tsx b/frontend/components/group/group-actions.tsx
index 2103bc6..d292296 100644
--- a/frontend/components/group/group-actions.tsx
+++ b/frontend/components/group/group-actions.tsx
@@ -110,18 +110,26 @@ async function logActivity(
  * Record a deposit in Supabase only after the transaction hash is verified
  * as successful on Horizon (see app/api/pools/deposit/route.ts). Verification
  * is retried briefly since Horizon may lag a freshly confirmed ledger.
+ *
+ * `tokenSymbol`/`tokenAmount` are optional and, when present, let the activity
+ * row be broken out by settlement currency (multi-token / SEP-41 deposits —
+ * see lib/deposit-token.ts).
  */
 async function verifyAndLogDeposit(
   poolId: string,
   userAddress: string,
   txHash: string,
-  amount: string | null
+  amount: string | null,
+  tokenSymbol?: string,
+  tokenAmount?: string | null
 ) {
   const payload = {
     poolId,
     userAddress,
     txHash,
     amount: amount ? parseFloat(amount) : null,
+    tokenSymbol,
+    tokenAmount: tokenAmount ?? amount ?? null,
   }
   for (let attempt = 0; attempt < 3; attempt++) {
     try {
@@ -419,7 +427,7 @@ export function GroupActions({
 
         if (txHash) {
           updateTxHash(txHash)
-          await verifyAndLogDeposit(groupId, address, txHash, depositAmount || null)
+          await verifyAndLogDeposit(groupId, address, txHash, depositAmount || null, tokenSymbol)
           void triggerPushNotification(
             groupId,
             "event_deposit",
diff --git a/frontend/lib/deposit-token.test.ts b/frontend/lib/deposit-token.test.ts
new file mode 100644
index 0000000..bb6df85
--- /dev/null
+++ b/frontend/lib/deposit-token.test.ts
@@ -0,0 +1,125 @@
+// Unit tests for the pure multi-token deposit logic: decimals conversion,
+// token selection, balance checks and fee maths.
+import { test } from "node:test"
+import assert from "node:assert"
+import {
+  baseUnitsToHuman,
+  checkSufficientBalance,
+  computeDepositFee,
+  humanToBaseUnits,
+  normalizeDecimals,
+  trimHumanAmount,
+  validateTokenSelection,
+  type DepositToken,
+} from "./deposit-token"
+
+const XLM: DepositToken = { contractAddress: "native", symbol: "XLM", decimals: 7 }
+const USDC: DepositToken = {
+  contractAddress: "CBIELTK6YBZJU5UP2WWQEUCYKLPU6AUNZ2BQ4WWFEIE3USCIHMXQDAMA",
+  symbol: "USDC",
+  decimals: 7,
+}
+
+// ── Decimals & unit conversion ───────────────────────────────────────────────
+
+test("normalizeDecimals - falls back to 7 for invalid values", () => {
+  assert.equal(normalizeDecimals(7), 7)
+  assert.equal(normalizeDecimals(0), 0)
+  assert.equal(normalizeDecimals(undefined), 7)
+  assert.equal(normalizeDecimals(null), 7)
+  assert.equal(normalizeDecimals(-1), 7)
+  assert.equal(normalizeDecimals(3.5), 7)
+  assert.equal(normalizeDecimals(Number.NaN), 7)
+})
+
+test("humanToBaseUnits - converts human amount to exact base units", () => {
+  assert.equal(humanToBaseUnits("1", 7), 10000000n)
+  assert.equal(humanToBaseUnits("1.5", 7), 15000000n)
+  assert.equal(humanToBaseUnits("0.07", 7), 700000n)
+  assert.equal(humanToBaseUnits("100", 0), 100n)
+  assert.equal(humanToBaseUnits(1.5, 7), 15000000n)
+})
+
+test("humanToBaseUnits - rejects invalid input", () => {
+  assert.equal(humanToBaseUnits("", 7), null)
+  assert.equal(humanToBaseUnits("abc", 7), null)
+  assert.equal(humanToBaseUnits("-1", 7), null)
+  assert.equal(humanToBaseUnits("1.2.3", 7), null)
+  assert.equal(humanToBaseUnits("0.12345678", 7), null) // too many decimals
+  assert.equal(humanToBaseUnits("1e5", 7), null)
+})
+
+test("baseUnitsToHuman - is the inverse of humanToBaseUnits", () => {
+  assert.equal(baseUnitsToHuman(15000000n, 7), "1.5000000")
+  assert.equal(baseUnitsToHuman(700000n, 7), "0.0700000")
+  assert.equal(baseUnitsToHuman(100n, 0), "100")
+  assert.equal(baseUnitsToHuman(1n, 7), "0.0000001")
+  assert.equal(baseUnitsToHuman(0n, 7), "0.0000000")
+})
+
+test("trimHumanAmount - trims trailing zeros in display", () => {
+  assert.equal(trimHumanAmount("1.5000000"), "1.5")
+  assert.equal(trimHumanAmount("1.0000000"), "1")
+  assert.equal(trimHumanAmount("0.0700000"), "0.07")
+  assert.equal(trimHumanAmount("100"), "100")
+})
+
+// ── Token selection ──────────────────────────────────────────────────────────
+
+test("validateTokenSelection - accepts a supported token", () => {
+  const r = validateTokenSelection(XLM, [XLM, USDC])
+  assert.equal(r.ok, true)
+  if (r.ok) assert.equal(r.token.symbol, "XLM")
+})
+
+test("validateTokenSelection - accepts native when supported list has native", () => {
+  const r = validateTokenSelection({ ...XLM }, [
+    { contractAddress: "native", symbol: "XLM", decimals: 7 },
+  ])
+  assert.equal(r.ok, true)
+})
+
+test("validateTokenSelection - rejects an unsupported token", () => {
+  const r = validateTokenSelection(USDC, [XLM])
+  assert.equal(r.ok, false)
+  if (!r.ok) assert.match(r.reason, /not supported/)
+})
+
+test("validateTokenSelection - unrestricted pool accepts any token", () => {
+  const r = validateTokenSelection(USDC, [])
+  assert.equal(r.ok, true)
+})
+
+// ── Balance checks ───────────────────────────────────────────────────────────
+
+test("checkSufficientBalance - ok when amount fits balance", () => {
+  const r = checkSufficientBalance("1.5", 20000000n, 7)
+  assert.equal(r.ok, true)
+  if (r.ok) assert.equal(r.baseUnits, 15000000n)
+})
+
+test("checkSufficientBalance - rejects insufficient balance", () => {
+  const r = checkSufficientBalance("3", 20000000n, 7)
+  assert.equal(r.ok, false)
+  if (!r.ok) assert.match(r.reason, /Insufficient/)
+})
+
+test("checkSufficientBalance - rejects zero and invalid amounts", () => {
+  assert.equal(checkSufficientBalance("0", 20000000n, 7).ok, false)
+  assert.equal(checkSufficientBalance("abc", 20000000n, 7).ok, false)
+})
+
+// ── Fee maths ────────────────────────────────────────────────────────────────
+
+test("computeDepositFee - computes fee and net in human units", () => {
+  // 100 XLM @ 10000 stroops, 2% treasury + 1% relayer = 3% → fee 3, net 97
+  const r = computeDepositFee("100", 200, 100, 7)
+  assert.equal(r.feeHuman, 3)
+  assert.equal(r.netHuman, 97)
+})
+
+test("computeDepositFee - zero fees pass through", () => {
+  const r = computeDepositFee("50", 0, 0, 7)
+  assert.equal(r.feeHuman, 0)
+  assert.equal(r.netHuman, 50)
+})
diff --git a/frontend/lib/deposit-token.ts b/frontend/lib/deposit-token.ts
new file mode 100644
index 0000000..3b65d5d
--- /dev/null
+++ b/frontend/lib/deposit-token.ts
@@ -0,0 +1,213 @@
+/**
+ * Pure logic behind end-to-end multi-token (SEP-41) deposits.
+ *
+ * A pool may accept deposits in more than one settlement token (see the
+ * contract's `set_supported_tokens` / `get_supported_tokens`). The deposit
+ * flow — UI token picker, balance/trustline checks, and the deposit API route —
+ * all share the same amount maths, so it lives here as a dependency-free,
+ * unit-testable module (mirroring `deposit-calendar.ts` / `batch-deposit.ts`).
+ *
+ * The two things every caller needs:
+ *  1. the right decimals for the chosen asset (7 for native XLM, or the
+ *     SEP-41 contract's decimals otherwise), and
+ *  2. converting between the *human* unit shown in the UI and the *base* unit
+ *     (stroops / raw integer) the contract and Horizon deal in — always the
+ *     reverse of what a naive `amount * 10 ** decimals` would assume.
+ */
+
+// ── Types ────────────────────────────────────────────────────────────────────
+
+/** A token the pool's deposit flow can accept, with display + maths metadata. */
+export interface DepositToken {
+  /** "native" for XLM, or a C… SAC/token contract id. */
+  contractAddress: string
+  /** e.g. "XLM" or "USDC". */
+  symbol: string
+  /** Stellar asset decimals (7 for native XLM and for SAC-wrapped tokens). */
+  decimals: number
+}
+
+/** Result of validating that a chosen token is actually acceptable. */
+export type TokenSelectionResult = { ok: true; token: DepositToken } | { ok: false; reason: string }
+
+/** Result of validating a user-entered human amount against an on-chain balance. */
+export type BalanceCheckResult = { ok: true; baseUnits: bigint } | { ok: false; reason: string }
+
+// ── Constants ────────────────────────────────────────────────────────────────
+
+/** Native XLM uses 7 decimals (stroops) on Stellar. */
+export const NATIVE_DECIMALS = 7
+
+/** The contract caps how many SEP-41 trustlines an account can hold. */
+export const MAX_TRUSTLINES = 7
+
+/** Maximum digits of precision we allow in a human amount input (>= 0). */
+const MAX_AMOUNT_DIGITS = 20
+
+// ── Decimals & unit conversion ───────────────────────────────────────────────
+
+/** Guard a decimals value: must be a safe, non-negative integer (Stellar caps
+ * asset decimals at 7, but custom tokens may be lower). Falls back to native. */
+export function normalizeDecimals(decimals: number | null | undefined): number {
+  if (
+    typeof decimals !== "number" ||
+    !Number.isFinite(decimals) ||
+    decimals < 0 ||
+    Math.floor(decimals) !== decimals
+  ) {
+    return NATIVE_DECIMALS
+  }
+  return decimals
+}
+
+/**
+ * Convert a human amount (e.g. "1.5") into base units for a token with the
+ * given decimals, i.e. the integer the contract/Horizon expect. Returns
+ * `null` when the input is not a finite, non-negative decimal number, so
+ * callers can show a validation error instead of minting a bogus value.
+ *
+ * Safe against floating-point error (e.g. `humanToBaseUnits("0.07", 7)`
+ * must be exactly `7000000`, not `6999999`).
+ */
+export function humanToBaseUnits(amount: number | string, decimals: number): bigint | null {
+  const normalized = normalizeDecimals(decimals)
+  const raw = typeof amount === "number" ? String(amount) : amount
+  const trimmed = raw.trim()
+  if (trimmed === "") return null
+  if (!/^\d+(\.\d+)?$/.test(trimmed)) return null
+
+  const [intPart, fracPart = ""] = trimmed.split(".")
+  if (intPart.length > MAX_AMOUNT_DIGITS) return null
+  if (fracPart.length > normalized) return null
+
+  // Left-pad the fractional part to the token's decimals, then join into one
+  // integer string. "1.5" @ 7 decimals → "1" + "5000000" → "15000000".
+  const paddedFrac = fracPart.padEnd(normalized, "0")
+  const joined = `${intPart}${paddedFrac}`
+  try {
+    return BigInt(joined)
+  } catch {
+    return null
+  }
+}
+
+/**
+ * Convert base units (stroops) back into a human amount string for a token
+ * with the given decimals. Inverse of `humanToBaseUnits`. e.g.
+ * `baseUnitsToHuman(7000000n, 7)` → "0.7000000". Trailing zeros beyond the
+ * integer part are preserved to match the token's precision so callers can
+ * format consistently with the repo's number conventions.
+ */
+export function baseUnitsToHuman(baseUnits: bigint, decimals: number): string {
+  const normalized = normalizeDecimals(decimals)
+  const negative = baseUnits < 0n
+  const abs = negative ? -baseUnits : baseUnits
+  const str = abs.toString()
+  if (normalized === 0) return negative ? `-${str}` : str
+
+  if (str.length <= normalized) {
+    const padded = str.padStart(normalized + 1, "0")
+    const int = padded.slice(0, -normalized)
+    const frac = padded.slice(-normalized)
+    return `${negative ? "-" : ""}${int}.${frac}`
+  }
+  const int = str.slice(0, -normalized)
+  const frac = str.slice(-normalized)
+  return `${negative ? "-" : ""}${int}.${frac}`
+}
+
+/**
+ * Trim trailing zeros from a base-units-derived human string so display
+ * reads "1.5" instead of "1.5000000" (keeping at least the integer part).
+ */
+export function trimHumanAmount(human: string): string {
+  if (!human.includes(".")) return human
+  const [int, frac] = human.split(".")
+  const trimmedFrac = frac.replace(/0+$/, "")
+  return trimmedFrac === "" ? int : `${int}.${trimmedFrac}`
+}
+
+// ── Token selection ──────────────────────────────────────────────────────────
+
+/**
+ * Resolve a chosen token against the pool's allowed set (the contract's
+ * `get_supported_tokens`, mapped to `DepositToken`s). A token is acceptable
+ * when its contract address matches a supported one (with `"native"` treated
+ * as the native XLM SAC). Empty supported list = unrestricted (pool only ever
+ * holds its single `initialize()` token).
+ */
+export function validateTokenSelection(
+  candidate: DepositToken,
+  supported: DepositToken[]
+): TokenSelectionResult {
+  const address = candidate.contractAddress
+  const isNative = address === "native"
+  const exact = supported.find(
+    (s) => s.contractAddress === address || (isNative && s.contractAddress === "native")
+  )
+
+  if (exact) return { ok: true, token: exact }
+  // Unrestricted pools: any single candidate is accepted as-is.
+  if (supported.length === 0) return { ok: true, token: candidate }
+
+  return {
+    ok: false,
+    reason: `Token ${candidate.symbol} is not supported by this pool`,
+  }
+}
+
+// ── Balance & trustline checks ───────────────────────────────────────────────
+
+/**
+ * Validate a human deposit amount against an on-chain base-units balance
+ * (from `fetchTokenBalance`). The `balance` is already in base units; we
+ * convert the user's human input to base units for a like-for-like comparison
+ * so a 7-decimals token compares correctly even at low values.
+ */
+export function checkSufficientBalance(
+  humanAmount: number | string,
+  balanceBaseUnits: bigint,
+  decimals: number
+): BalanceCheckResult {
+  const amountBase = humanToBaseUnits(humanAmount, decimals)
+  if (amountBase === null) {
+    return { ok: false, reason: "Enter a valid amount" }
+  }
+  if (amountBase <= 0n) {
+    return { ok: false, reason: "Amount must be greater than zero" }
+  }
+  if (amountBase > balanceBaseUnits) {
+    return { ok: false, reason: "Insufficient balance for this deposit" }
+  }
+  return { ok: true, baseUnits: amountBase }
+}
+
+// ── Fee maths ────────────────────────────────────────────────────────────────
+
+/**
+ * Compute the treasury + relayer fee on a human deposit amount, in the
+ * *same* human unit as `humanAmount`. The contract applies these basis points
+ * to the settlement token, so we compute on the human number and return the
+ * human fee amount (with the token's decimals preserved for display).
+ *
+ * @param humanAmount deposit amount in human units
+ * @param treasuryFeeBps treasury fee in basis points (10000 = 100%)
+ * @param relayerFeeBps relayer fee in basis points (10000 = 100%)
+ * @param decimals token decimals (for rounding)
+ * @returns `{ feeHuman, netHuman }` where netHuman = amount − fee
+ */
+export function computeDepositFee(
+  humanAmount: number | string,
+  treasuryFeeBps: number,
+  relayerFeeBps: number,
+  decimals: number
+): { feeHuman: number; netHuman: number } {
+  const base = humanToBaseUnits(humanAmount, decimals) ?? 0n
+  const totalBps = (treasuryFeeBps || 0) + (relayerFeeBps || 0)
+  const feeBase = (base * BigInt(totalBps)) / 10000n
+  const netBase = base - feeBase
+  return {
+    feeHuman: Number(baseUnitsToHuman(feeBase, decimals)),
+    netHuman: Number(baseUnitsToHuman(netBase, decimals)),
+  }
+}
diff --git a/frontend/package.json b/frontend/package.json
index 53b3a35..cf69a2d 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -12,7 +12,7 @@
     "format": "prettier --write .",
     "format:check": "prettier --check .",
     "start": "next start",
-    "test:unit": "tsx --test lib/csv-export.test.ts lib/activity-query.test.ts lib/soroban-event-mapping.test.ts lib/analytics.test.ts lib/batch-deposit.test.ts lib/deposit-calendar.test.ts lib/ical-export.test.ts lib/pool-health.test.ts lib/form-validation.test.ts lib/member-filters.test.ts lib/contract-version.test.ts lib/error-reporting.test.ts lib/pending-transactions.test.ts hooks/use-keyboard-shortcuts.test.ts app/api/admin/audit-log/route.test.ts app/api/admin/actions/route.test.ts app/api/errors/route.test.ts components/error-boundary.test.ts app/api/notifications/route.test.ts app/api/user-profile/route.test.ts app/api/notifications/digest-preferences/route.test.ts app/api/notifications/digest/unsubscribe/route.test.ts app/api/cron/send-digests/route.test.ts app/api/portfolio/summary/route.test.ts app/api/templates/route.test.ts",
+    "test:unit": "tsx --test lib/csv-export.test.ts lib/activity-query.test.ts lib/soroban-event-mapping.test.ts lib/analytics.test.ts lib/batch-deposit.test.ts lib/deposit-calendar.test.ts lib/deposit-token.test.ts lib/ical-export.test.ts lib/pool-health.test.ts lib/form-validation.test.ts lib/member-filters.test.ts lib/contract-version.test.ts lib/error-reporting.test.ts lib/pending-transactions.test.ts hooks/use-keyboard-shortcuts.test.ts app/api/admin/audit-log/route.test.ts app/api/admin/actions/route.test.ts app/api/errors/route.test.ts components/error-boundary.test.ts app/api/notifications/route.test.ts app/api/user-profile/route.test.ts app/api/notifications/digest-preferences/route.test.ts app/api/notifications/digest/unsubscribe/route.test.ts app/api/cron/send-digests/route.test.ts app/api/portfolio/summary/route.test.ts app/api/templates/route.test.ts",
     "test:components": "vitest run",
     "test:components:coverage": "vitest run --coverage",
     "test:e2e": "playwright test",