diff --git a/middleware/rateLimiter.js b/middleware/rateLimiter.js
index 7da69f9..5d2bcc6 100644
--- a/middleware/rateLimiter.js
+++ b/middleware/rateLimiter.js
@@ -21,6 +21,25 @@ const loginLimiter = makeLimiter(
   'Too many login attempts. Please try again in 15 minutes.',
 );
 
+// 5 FAILED login attempts per 15 minutes per username — layered on top of the
+// per-IP limiter so a distributed attacker (or many clients behind one NAT/proxy
+// sharing an IP bucket) cannot brute-force a single account. Successful logins
+// don't count toward the limit, so legitimate users are unaffected.
+const loginUsernameLimiter = rateLimit({
+  windowMs: 15 * 60 * 1000,
+  max: 5,
+  standardHeaders: 'draft-7',
+  legacyHeaders: false,
+  skipSuccessfulRequests: true,
+  keyGenerator: (req) => {
+    const username = String(req.body?.username || '').trim().toLowerCase();
+    return username ? `user:${username}` : ipKeyGenerator(req);
+  },
+  handler(req, res) {
+    res.status(429).json({ error: 'Too many failed login attempts for this account. Please try again in 15 minutes.' });
+  },
+});
+
 // 5 password-change attempts per 15 minutes per IP
 const passwordLimiter = makeLimiter(
   5, 15 * 60 * 1000,
@@ -78,6 +97,7 @@ const syncLimiter = rateLimit({
 // ── Export all limiters plus reset function ────────────────────────────────────
 const allLimiters = [
   loginLimiter,
+  loginUsernameLimiter,
   passwordLimiter,
   importLimiter,
   exportLimiter,
@@ -98,6 +118,7 @@ function resetStores() {
 
 module.exports = {
   loginLimiter,
+  loginUsernameLimiter,
   passwordLimiter,
   importLimiter,
   exportLimiter,
diff --git a/routes/bills.js b/routes/bills.js
index 5275f2b..bc5b0f8 100644
--- a/routes/bills.js
+++ b/routes/bills.js
@@ -21,6 +21,7 @@ const {
   accountingActiveSql,
   applyBankPaymentAsSourceOfTruth,
 } = require('../services/paymentAccountingService');
+const { localDateString, todayLocal } = require('../utils/dates');
 
 // ── GET /api/bills ────────────────────────────────────────────────────────────
 router.get('/', (req, res) => {
@@ -139,7 +140,7 @@ router.post('/:id/snooze-drift', (req, res) => {
   if (!bill || bill.user_id !== req.user.id) return res.status(404).json({ error: 'Not found' });
   const until = new Date();
   until.setDate(until.getDate() + 30);
-  const untilStr = until.toISOString().slice(0, 10);
+  const untilStr = localDateString(until);
   db.prepare('UPDATE bills SET drift_snoozed_until = ? WHERE id = ?').run(untilStr, id);
   res.json({ ok: true, drift_snoozed_until: untilStr });
 });
@@ -455,7 +456,7 @@ router.put('/:id', (req, res) => {
   const inactiveReason = typeof req.body.inactive_reason === 'string' ? req.body.inactive_reason.trim() || null : null;
   const wasActive = existing.active === 1;
   const nowActive = normalized.active === 1;
-  const inactivatedAt = (!wasActive || nowActive) ? existing.inactivated_at : (inactiveReason ? new Date().toISOString().slice(0, 10) : existing.inactivated_at);
+  const inactivatedAt = (!wasActive || nowActive) ? existing.inactivated_at : (inactiveReason ? todayLocal() : existing.inactivated_at);
 
   db.prepare(`
     UPDATE bills SET
@@ -726,7 +727,7 @@ router.post('/:id/toggle-paid', (req, res) => {
     const day = Math.min(Math.max(Number(bill.due_day), 1), daysInMonth);
     paidDate = `${year}-${String(month).padStart(2, '0')}-${String(day).padStart(2, '0')}`;
   } else if (!paidDate) {
-    paidDate = new Date().toISOString().slice(0, 10);
+    paidDate = todayLocal();
   }
   
   const method = req.body.method || null;
@@ -1239,7 +1240,7 @@ router.post('/:id/merchant-rules/import-historical', (req, res) => {
             if (dom <= 5) {
               const prevEnd = new Date(paid.getFullYear(), paid.getMonth(), 0);
               if (rules2.due_day <= prevEnd.getDate()) {
-                const suggested = prevEnd.toISOString().slice(0, 10);
+                const suggested = localDateString(prevEnd);
                 if (insertedPayment) {
                   lateAttributions.push({ payment_id: insertedPayment.id, bill_name: bill.name, original_date: paidDate, suggested_date: suggested, amount });
                 }
diff --git a/routes/calendar.js b/routes/calendar.js
index 904af6f..25636fb 100644
--- a/routes/calendar.js
+++ b/routes/calendar.js
@@ -13,6 +13,7 @@ const {
   regenerateToken,
   revokeToken,
 } = require('../services/calendarFeedService');
+const { localDateString } = require('../utils/dates');
 
 function clampDay(year, month, day) {
   const daysInMonth = new Date(year, month, 0).getDate();
@@ -106,7 +107,7 @@ router.get('/', (req, res) => {
     return res.status(400).json(standardizeError('month must be an integer between 1 and 12', 'VALIDATION_ERROR', 'month'));
   }
 
-  const today = now.toISOString().slice(0, 10);
+  const today = localDateString(now);
   const userSettings = getUserSettings(req.user.id);
   const rowOptions = { gracePeriodDays: userSettings.grace_period_days };
   const daysInMonth = new Date(year, month, 0).getDate();
diff --git a/routes/matches.js b/routes/matches.js
index a78eaec..f672b83 100644
--- a/routes/matches.js
+++ b/routes/matches.js
@@ -7,6 +7,7 @@ const {
   rejectMatchSuggestion,
 } = require('../services/matchSuggestionService');
 const { learnMerchantRuleFromMatch } = require('../services/billMerchantRuleService');
+const { todayLocal } = require('../utils/dates');
 
 function sendMatchError(res, err, fallbackMessage = 'Match operation failed') {
   if (err.status) {
@@ -55,7 +56,7 @@ router.post('/confirm', (req, res) => {
   const existing = db.prepare('SELECT id FROM payments WHERE transaction_id = ? AND deleted_at IS NULL').get(txId);
   if (existing) return res.status(409).json(standardizeError('A payment is already linked to this transaction', 'DUPLICATE_MATCH'));
 
-  const paidDate = tx.posted_date || (tx.transacted_at ? tx.transacted_at.slice(0, 10) : new Date().toISOString().slice(0, 10));
+  const paidDate = tx.posted_date || (tx.transacted_at ? tx.transacted_at.slice(0, 10) : todayLocal());
   const amount   = Math.round(Math.abs(tx.amount)) / 100; // cents → dollars
 
   try {
diff --git a/routes/payments.js b/routes/payments.js
index 75b911e..6b06f5d 100644
--- a/routes/payments.js
+++ b/routes/payments.js
@@ -9,6 +9,7 @@ const {
   markProvisionalManualPaymentsOverridden,
   reactivatePaymentsOverriddenBy,
 } = require('../services/paymentAccountingService');
+const { todayLocal } = require('../utils/dates');
 
 // SQL_NOT_DELETED is a compile-time constant SQL fragment, never user-supplied.
 // It cannot be a bind parameter (SQL fragments are not parameterisable — only
@@ -230,7 +231,7 @@ router.post('/quick', (req, res) => {
   const paymentValidation = validatePaymentInput(
     {
       amount: amount != null ? amount : bill.expected_amount,
-      paid_date: paid_date || new Date().toISOString().slice(0, 10),
+      paid_date: paid_date || todayLocal(),
       payment_source: payment_source ?? 'manual',
     },
     { requireBillId: false },
@@ -267,7 +268,7 @@ router.post('/autopay-suggestions/:billId/confirm', (req, res) => {
   const context = getAutopaySuggestionContext(db, req.user.id, billId, ym.year, ym.month);
   if (context.error) return res.status(context.status).json(context.error);
   const { bill, dueDate, amount } = context;
-  if (dueDate > new Date().toISOString().slice(0, 10)) {
+  if (dueDate > todayLocal()) {
     return res.status(400).json(standardizeError('Autopay suggestion is not due yet', 'VALIDATION_ERROR', 'paid_date'));
   }
   const paymentValidation = validatePaymentInput(
@@ -574,7 +575,7 @@ router.patch('/:id/attribute-to-month', (req, res) => {
     return res.status(400).json(standardizeError('paid_date must be YYYY-MM-DD', 'VALIDATION_ERROR', 'paid_date'));
   }
   // Validate it is a real calendar date
-  const newDate = new Date(paid_date + 'T00:00:00');
+  const newDate = new Date(paid_date + 'T00:00:00Z');
   if (isNaN(newDate.getTime()) || newDate.toISOString().slice(0, 10) !== paid_date) {
     return res.status(400).json(standardizeError('paid_date is not a valid calendar date', 'VALIDATION_ERROR', 'paid_date'));
   }
diff --git a/routes/status.js b/routes/status.js
index 5b03321..667ea4f 100644
--- a/routes/status.js
+++ b/routes/status.js
@@ -10,6 +10,7 @@ const { checkForUpdates } = require('../services/updateCheckService');
 const { getStatus: getBankSyncWorkerStatus } = require('../services/bankSyncWorker');
 const { getBankSyncConfig } = require('../services/bankSyncConfigService');
 const { accountingActiveSql } = require('../services/paymentAccountingService');
+const { localDateString } = require('../utils/dates');
 
 const startTime = Date.now();
 let pkg;
@@ -339,7 +340,7 @@ router.get('/', async (req, res) => {
     ok: true,
     time: now.toISOString(),
     now: now.toISOString(),
-    today: now.toISOString().slice(0, 10),
+    today: localDateString(now),
     timezone: Intl.DateTimeFormat().resolvedOptions().timeZone || process.env.TZ || null,
     utc_offset: -now.getTimezoneOffset() / 60,
     env: process.env.NODE_ENV || 'development',
diff --git a/routes/transactions.js b/routes/transactions.js
index 90af143..799d255 100644
--- a/routes/transactions.js
+++ b/routes/transactions.js
@@ -14,6 +14,7 @@ const {
   unmatchTransaction,
 } = require('../services/transactionMatchService');
 const { reactivatePaymentsOverriddenBy } = require('../services/paymentAccountingService');
+const { todayLocal } = require('../utils/dates');
 
 const MATCH_STATUSES = new Set(['unmatched', 'matched', 'ignored']);
 const SOURCE_TYPES = new Set(['manual', 'file_import', 'provider_sync']);
@@ -28,7 +29,7 @@ const TEXT_FIELDS = {
 };
 
 function todayStr() {
-  return new Date().toISOString().slice(0, 10);
+  return todayLocal();
 }
 
 function cleanText(value, maxLength) {
diff --git a/server.js b/server.js
index 569cd4b..57d68ce 100644
--- a/server.js
+++ b/server.js
@@ -8,7 +8,7 @@ const { recordError }                             = require('./services/statusRu
 const { securityHeaders }                         = require('./middleware/securityHeaders');
 const { logAudit }                                = require('./services/auditService');
 const { errorFormatter }                          = require('./middleware/errorFormatter');
-const { importLimiter, exportLimiter, adminActionLimiter, oidcLimiter, loginLimiter, passwordLimiter, backupOperationLimiter } =
+const { importLimiter, exportLimiter, adminActionLimiter, oidcLimiter, loginLimiter, loginUsernameLimiter, passwordLimiter, backupOperationLimiter } =
   require('./middleware/rateLimiter');
 const { csrfMiddleware, csrfTokenProvider }                     = require('./middleware/csrf');
 
@@ -86,8 +86,12 @@ function skipRateLimitIfNoUsers(limiter) {
 }
 
 // Mount login router with conditional rate limiting
-// If no users exist, rate limit is bypassed; otherwise it applies
+// If no users exist, rate limit is bypassed; otherwise it applies.
+// Two layers: per-IP (all attempts) and per-username (failed attempts only),
+// so one IP can't burn 10 tries against every account, and a distributed
+// attacker can't brute-force a single account from many IPs.
 app.use('/api/auth/login', skipRateLimitIfNoUsers(loginLimiter));
+app.use('/api/auth/login', skipRateLimitIfNoUsers(loginUsernameLimiter));
 // Login skips CSRF inside routes/auth because no authenticated session exists yet.
 // Authenticated state-changing auth routes, including logout-all and password
 // changes, require the SPA's x-csrf-token header like other mutating requests.
diff --git a/services/billMerchantRuleService.js b/services/billMerchantRuleService.js
index 507af78..ac06a08 100644
--- a/services/billMerchantRuleService.js
+++ b/services/billMerchantRuleService.js
@@ -3,6 +3,7 @@
 const { normalizeMerchant } = require('./subscriptionService');
 const { getUserSettings } = require('./userSettings');
 const { applyBankPaymentAsSourceOfTruth } = require('./paymentAccountingService');
+const { localDateString } = require('../utils/dates');
 
 // Word-boundary merchant match — requires the rule to appear as complete word(s)
 // within the transaction string (or vice versa), not just as a substring.
@@ -25,7 +26,7 @@ function lateAttributionCandidate(paidDateStr, dueDayOfMonth, graceDays = 5) {
   if (dayOfMonth > graceDays) return null;
   const prevMonthLastDay = new Date(paid.getFullYear(), paid.getMonth(), 0);
   if (dueDayOfMonth > prevMonthLastDay.getDate()) return null;
-  return prevMonthLastDay.toISOString().slice(0, 10); // suggested prior-month date
+  return localDateString(prevMonthLastDay); // suggested prior-month date
 }
 
 // Persist a merchant→bill rule so future synced transactions auto-match.
diff --git a/services/billsService.js b/services/billsService.js
index 3922205..c7dfaa3 100644
--- a/services/billsService.js
+++ b/services/billsService.js
@@ -1,3 +1,4 @@
+const { monthKey } = require('../utils/dates');
 const VALID_VISIBILITY = ['default', 'all', 'ranges', 'none'];
 
 const TEMPLATE_FIELDS = [
@@ -478,7 +479,7 @@ function computeBalanceDelta(bill, paymentAmount) {
   if (!Number.isFinite(bal) || bal <= 0) return null;
   if (!Number.isFinite(amt) || amt <= 0)  return null;
 
-  const currentMonth  = new Date().toISOString().slice(0, 7); // "YYYY-MM"
+  const currentMonth  = monthKey(); // "YYYY-MM" (local time)
   const applyInterest = rate > 0 && bill.interest_accrued_month !== currentMonth;
   const interestDelta = applyInterest ? Math.round(bal * (rate / 100 / 12) * 100) / 100 : 0;
 
diff --git a/services/driftService.js b/services/driftService.js
index 11c3c3c..e404f56 100644
--- a/services/driftService.js
+++ b/services/driftService.js
@@ -4,6 +4,7 @@ const { getDb } = require('../db/database');
 const { getCycleRange } = require('./statusService');
 const { accountingActiveSql } = require('./paymentAccountingService');
 const { getUserSettings } = require('./userSettings');
+const { localDateString } = require('../utils/dates');
 
 const MONTHS_BACK  = 3;
 const MIN_PAID_MONTHS = 2;
@@ -37,7 +38,7 @@ function getDriftReport(userId, now = new Date()) {
       WHERE b.user_id = ? AND b.active = 1 AND b.deleted_at IS NULL
     `).all(userId);
 
-    const todayStr = now.toISOString().slice(0, 10);
+    const todayStr = localDateString(now);
     const drifted  = [];
 
     const mbsStmt = db.prepare(
diff --git a/services/notificationService.js b/services/notificationService.js
index d0e6c78..0497c45 100644
--- a/services/notificationService.js
+++ b/services/notificationService.js
@@ -7,6 +7,7 @@ const {
   markNotificationSuccess,
   markNotificationTestSuccess,
 } = require('./statusRuntime');
+const { localDateString } = require('../utils/dates');
 
 // ── Push notification channels ────────────────────────────────────────────────
 
@@ -279,7 +280,7 @@ async function runNotifications() {
   const now   = new Date();
   const year  = now.getFullYear();
   const month = now.getMonth() + 1;
-  const today = now.toISOString().slice(0, 10);
+  const today = localDateString(now);
 
   const { getCycleRange, resolveDueDate } = require('./statusService');
 
@@ -315,7 +316,7 @@ async function runNotifications() {
   // and the per-bill cycle check happens in memory below.
   const billIds = bills.map(b => b.id);
   const monthStart = `${year}-${String(month).padStart(2, '0')}-01`;
-  const monthEnd   = new Date(year, month, 0).toISOString().slice(0, 10);
+  const monthEnd   = localDateString(new Date(year, month, 0));
   const paidMap = new Map();
   if (billIds.length > 0) {
     const placeholders = billIds.map(() => '?').join(',');
@@ -504,7 +505,7 @@ async function runDriftNotifications() {
   const now   = new Date();
   const year  = now.getFullYear();
   const month = now.getMonth() + 1;
-  const today = now.toISOString().slice(0, 10);
+  const today = localDateString(now);
 
   const allowUserConfig  = getSetting('notify_allow_user_config') === 'true';
   const globalRecipient  = getSetting('notify_global_recipient');
diff --git a/services/simplefinService.js b/services/simplefinService.js
index fa82fa6..93eed1c 100644
--- a/services/simplefinService.js
+++ b/services/simplefinService.js
@@ -1,5 +1,6 @@
 'use strict';
 
+
 // SimpleFIN consumer client.
 //
 // This module handles the protocol-level work: claiming tokens, fetching
@@ -170,6 +171,10 @@ function normalizeTransaction(rawTx, localAccountId, dataSourceId, userId, accou
   const amount     = Math.round(parseFloat(rawTx.amount) * 100);
   // Pending transactions report posted = 0 (or omit it) until they settle.
   const isPending  = rawTx.pending === true || rawTx.pending === 1;
+  // NOTE: deliberately a UTC slice, not localDateString(). SimpleFIN encodes
+  // the posted *date* as an epoch at UTC midnight, so the UTC calendar day IS
+  // the bank's posting date; converting to server-local time would shift it
+  // back a day for any timezone west of UTC.
   const postedDate = (rawTx.posted && !isPending)
     ? new Date(rawTx.posted * 1000).toISOString().slice(0, 10)
     : null;
diff --git a/services/spendingService.js b/services/spendingService.js
index f245253..099c07e 100644
--- a/services/spendingService.js
+++ b/services/spendingService.js
@@ -1,6 +1,7 @@
 'use strict';
 
 const { normalizeMerchant } = require('./subscriptionService');
+const { localDateString } = require('../utils/dates');
 
 // Spending = unmatched outflows (amount < 0) that haven't been ignored.
 // Bill-matched transactions are excluded so there's no double-counting.
@@ -13,7 +14,7 @@ const SPENDING_WHERE = `
 
 function monthRange(year, month) {
   const start = `${year}-${String(month).padStart(2, '0')}-01`;
-  const end   = new Date(year, month, 0).toISOString().slice(0, 10); // last day
+  const end   = localDateString(new Date(year, month, 0)); // last day
   return { start, end };
 }
 
diff --git a/services/subscriptionService.js b/services/subscriptionService.js
index c22e21c..2d2d8b3 100644
--- a/services/subscriptionService.js
+++ b/services/subscriptionService.js
@@ -1,6 +1,7 @@
 'use strict';
 
 const { billingCycleForCycleType, insertBill, validateBillData } = require('./billsService');
+const { localDateString, todayLocal } = require('../utils/dates');
 
 const SUBSCRIPTION_TYPES = [
   'streaming', 'software', 'cloud', 'music', 'news',
@@ -488,7 +489,7 @@ function nextDueDate(bill, now = new Date()) {
       date = new Date(date.getFullYear(), date.getMonth() + step, dueDay);
     }
   }
-  return date.toISOString().slice(0, 10);
+  return localDateString(date);
 }
 
 function decorateSubscription(bill) {
@@ -1024,7 +1025,7 @@ function searchSubscriptionTransactions(db, userId, query = {}) {
 }
 
 function createSubscriptionFromRecommendation(db, userId, payload = {}) {
-  const seenDate = payload.last_seen_date || new Date().toISOString().slice(0, 10);
+  const seenDate = payload.last_seen_date || todayLocal();
   const source = payload.catalog_match
     ? 'catalog_match'
     : 'simplefin_recommendation';
diff --git a/services/trackerService.js b/services/trackerService.js
index c978d47..efd3805 100644
--- a/services/trackerService.js
+++ b/services/trackerService.js
@@ -7,6 +7,7 @@ const { computeBalanceDelta, applyBalanceDelta } = require('./billsService');
 const { computeAmountSuggestion } = require('./amountSuggestionService');
 const { accountingActiveSql } = require('./paymentAccountingService');
 const { normalizeMerchant } = require('./subscriptionService');
+const { localDateString } = require('../utils/dates');
 
 const DEFAULT_PENDING_DAYS = 3;
 
@@ -414,7 +415,7 @@ function getTracker(userId, query = {}, now = new Date()) {
 
   const db = getDb();
   const { year, month } = parsed;
-  const todayStr = now.toISOString().slice(0, 10);
+  const todayStr = localDateString(now);
   const userSettings = getUserSettings(userId);
   const rowOptions = { gracePeriodDays: userSettings.grace_period_days };
   const { start, end } = getCycleRange(year, month);
@@ -593,14 +594,14 @@ function getTracker(userId, query = {}, now = new Date()) {
 function getUpcomingBills(userId, query = {}, now = new Date()) {
   const db = getDb();
   const days = Math.max(1, Math.min(parseInt(query.days || '30', 10) || 30, 365));
-  const todayStr = now.toISOString().slice(0, 10);
+  const todayStr = localDateString(now);
   const userSettings = getUserSettings(userId);
   const rowOptions = { gracePeriodDays: userSettings.grace_period_days };
   const bills = fetchActiveBills(db, userId, 'id');
 
   const cutoff = new Date(now);
   cutoff.setDate(cutoff.getDate() + days);
-  const cutoffStr = cutoff.toISOString().slice(0, 10);
+  const cutoffStr = localDateString(cutoff);
   const upcoming = [];
   const seen = new Set();
   const monthCount = (cutoff.getFullYear() - now.getFullYear()) * 12
@@ -645,7 +646,7 @@ function getUpcomingBills(userId, query = {}, now = new Date()) {
 
 function getOverdueCount(userId, now = new Date()) {
   const db = getDb();
-  const todayStr = now.toISOString().slice(0, 10);
+  const todayStr = localDateString(now);
   const year  = now.getFullYear();
   const month = now.getMonth() + 1;
   const monthStr = String(month).padStart(2, '0');
diff --git a/utils/dates.js b/utils/dates.js
index ba7bf78..f3078a8 100644
--- a/utils/dates.js
+++ b/utils/dates.js
@@ -30,4 +30,14 @@ function localDateStringDaysAgo(days, from = new Date()) {
   return localDateString(d);
 }
 
-module.exports = { localDateString, localYearMonth, localDateStringDaysAgo };
+/** Today as YYYY-MM-DD in local time. Alias of localDateString(). */
+function todayLocal() {
+  return localDateString(new Date());
+}
+
+/** YYYY-MM month key in local time (e.g. "2026-06"). */
+function monthKey(date = new Date()) {
+  return `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, '0')}`;
+}
+
+module.exports = { localDateString, localYearMonth, localDateStringDaysAgo, todayLocal, monthKey };