diff --git a/src/Host/FSH.Starter.Api/appsettings.json b/src/Host/FSH.Starter.Api/appsettings.json
index 60418ef856..5a9628a5f8 100644
--- a/src/Host/FSH.Starter.Api/appsettings.json
+++ b/src/Host/FSH.Starter.Api/appsettings.json
@@ -1,7 +1,7 @@
 {
   "Billing": {
     "DefaultPlanKey": "free",
-    "GraceWindowDays": 7
+    "GracePeriodDays": 7
   },
   "OpenTelemetryOptions": {
     "Enabled": true,
diff --git a/src/Modules/Identity/Modules.Identity/IdentityModule.cs b/src/Modules/Identity/Modules.Identity/IdentityModule.cs
index 74dafdcec3..f7f4da64ed 100644
--- a/src/Modules/Identity/Modules.Identity/IdentityModule.cs
+++ b/src/Modules/Identity/Modules.Identity/IdentityModule.cs
@@ -125,7 +125,7 @@ public void ConfigureServices(IHostApplicationBuilder builder)
         // Configure password policy options
         services.Configure<PasswordPolicyOptions>(builder.Configuration.GetSection("PasswordPolicy"));
 
-        // Tenant subscription grace window (shared "Billing" section) — used by the login expiry check.
+        // Tenant subscription grace period (shared "Billing" section) — used by the login expiry check.
         services.Configure<TenantGraceOptions>(builder.Configuration.GetSection(TenantGraceOptions.SectionName));
 
         // Register password history service
diff --git a/src/Modules/Identity/Modules.Identity/Services/IdentityService.cs b/src/Modules/Identity/Modules.Identity/Services/IdentityService.cs
index 635f071423..a403a2363e 100644
--- a/src/Modules/Identity/Modules.Identity/Services/IdentityService.cs
+++ b/src/Modules/Identity/Modules.Identity/Services/IdentityService.cs
@@ -23,7 +23,7 @@ public sealed class IdentityService : IIdentityService
     private readonly IGroupRoleService _groupRoleService;
     private readonly TimeProvider _timeProvider;
     private readonly IdentityDbContext _dbContext;
-    private readonly int _graceWindowDays;
+    private readonly int _gracePeriodDays;
 
     public IdentityService(
         UserManager<FshUser> userManager,
@@ -41,7 +41,7 @@ public IdentityService(
         _groupRoleService = groupRoleService;
         _timeProvider = timeProvider;
         _dbContext = dbContext;
-        _graceWindowDays = graceOptions.Value.GraceWindowDays;
+        _gracePeriodDays = graceOptions.Value.GracePeriodDays;
     }
 
     public async Task<(string Subject, IEnumerable<Claim> Claims)?>
@@ -286,9 +286,9 @@ private void ValidateTenantStatus(AppTenantInfo tenant)
             throw new UnauthorizedException($"tenant {tenant.Id} is deactivated");
         }
 
-        // Honor the billing grace window: a lapsed tenant can still authenticate until
+        // Honor the billing grace period: a lapsed tenant can still authenticate until
         // ValidUpto + grace (matching the request-time guard in MultitenancyModule).
-        if (_timeProvider.GetUtcNow().UtcDateTime > tenant.ValidUpto.AddDays(_graceWindowDays))
+        if (_timeProvider.GetUtcNow().UtcDateTime > tenant.ValidUpto.AddDays(_gracePeriodDays))
         {
             throw new UnauthorizedException($"tenant {tenant.Id} validity has expired");
         }
diff --git a/src/Modules/Identity/Modules.Identity/TenantGraceOptions.cs b/src/Modules/Identity/Modules.Identity/TenantGraceOptions.cs
index be0e2f4ea3..6bb26a5f46 100644
--- a/src/Modules/Identity/Modules.Identity/TenantGraceOptions.cs
+++ b/src/Modules/Identity/Modules.Identity/TenantGraceOptions.cs
@@ -1,12 +1,12 @@
 namespace FSH.Modules.Identity;
 
 /// <summary>
-/// Login-side view of the tenant billing grace window (config section <c>"Billing"</c>). A tenant
-/// whose subscription has lapsed can still authenticate until <c>ValidUpto + GraceWindowDays</c>.
+/// Login-side view of the tenant billing grace period (config section <c>"Billing"</c>). A tenant
+/// whose subscription has lapsed can still authenticate until <c>ValidUpto + GracePeriodDays</c>.
 /// </summary>
 public sealed class TenantGraceOptions
 {
     public const string SectionName = "Billing";
 
-    public int GraceWindowDays { get; set; } = 7;
+    public int GracePeriodDays { get; set; } = 7;
 }
diff --git a/src/Modules/Multitenancy/Modules.Multitenancy.Contracts/Dtos/TenantStatusDto.cs b/src/Modules/Multitenancy/Modules.Multitenancy.Contracts/Dtos/TenantStatusDto.cs
index 2f1ba77957..aee498877d 100644
--- a/src/Modules/Multitenancy/Modules.Multitenancy.Contracts/Dtos/TenantStatusDto.cs
+++ b/src/Modules/Multitenancy/Modules.Multitenancy.Contracts/Dtos/TenantStatusDto.cs
@@ -16,6 +16,6 @@ public sealed class TenantStatusDto
     /// <summary>Derived lifecycle state: "Active", "InGrace", or "Expired".</summary>
     public string ExpiryState { get; init; } = "Active";
 
-    /// <summary>Instant after which a lapsed tenant is hard-blocked (ValidUpto + grace window).</summary>
+    /// <summary>Instant after which a lapsed tenant is hard-blocked (ValidUpto + grace period).</summary>
     public DateTime GraceEndsUtc { get; init; }
 }
\ No newline at end of file
diff --git a/src/Modules/Multitenancy/Modules.Multitenancy.Contracts/Events/TenantEnteredGraceIntegrationEvent.cs b/src/Modules/Multitenancy/Modules.Multitenancy.Contracts/Events/TenantEnteredGraceIntegrationEvent.cs
index 8775f05b39..244c467e42 100644
--- a/src/Modules/Multitenancy/Modules.Multitenancy.Contracts/Events/TenantEnteredGraceIntegrationEvent.cs
+++ b/src/Modules/Multitenancy/Modules.Multitenancy.Contracts/Events/TenantEnteredGraceIntegrationEvent.cs
@@ -4,7 +4,7 @@ namespace FSH.Modules.Multitenancy.Contracts.Events;
 
 /// <summary>
 /// Raised by the daily expiry scan when a tenant has passed <c>ValidUpto</c> but is still inside the
-/// grace window (access continues). Consumers warn the tenant that the grace period is counting down.
+/// grace period (access continues). Consumers warn the tenant that the grace period is counting down.
 /// </summary>
 public sealed record TenantEnteredGraceIntegrationEvent(
     Guid Id,
diff --git a/src/Modules/Multitenancy/Modules.Multitenancy/MultitenancyModule.cs b/src/Modules/Multitenancy/Modules.Multitenancy/MultitenancyModule.cs
index a03b3539c6..fd157b1af1 100644
--- a/src/Modules/Multitenancy/Modules.Multitenancy/MultitenancyModule.cs
+++ b/src/Modules/Multitenancy/Modules.Multitenancy/MultitenancyModule.cs
@@ -175,10 +175,10 @@ public void ConfigureMiddleware(IApplicationBuilder app)
                         throw new ForbiddenException("This tenant has been deactivated. Contact your administrator.");
                     }
 
-                    // Expiry is enforced on every request (not just at login) with a grace window:
+                    // Expiry is enforced on every request (not just at login) with a grace period:
                     // a tenant past ValidUpto still works until ValidUpto + grace, then is hard-blocked.
                     var graceDays = ctx.RequestServices
-                        .GetRequiredService<IOptions<TenantBillingOptions>>().Value.GraceWindowDays;
+                        .GetRequiredService<IOptions<TenantBillingOptions>>().Value.GracePeriodDays;
                     var nowUtc = ctx.RequestServices.GetRequiredService<TimeProvider>().GetUtcNow().UtcDateTime;
                     var graceEndsUtc = tenant.ValidUpto.AddDays(graceDays);
                     if (nowUtc > graceEndsUtc)
@@ -186,7 +186,7 @@ public void ConfigureMiddleware(IApplicationBuilder app)
                         throw new ForbiddenException("This tenant's subscription has expired. Please renew to continue.");
                     }
 
-                    // Inside the grace window: surface days-left so clients can warn. Set via OnStarting so
+                    // Inside the grace period: surface days-left so clients can warn. Set via OnStarting so
                     // the header survives even when an exception handler rewrites the response.
                     if (nowUtc > tenant.ValidUpto)
                     {
diff --git a/src/Modules/Multitenancy/Modules.Multitenancy/Services/TenantExpiryScanJob.cs b/src/Modules/Multitenancy/Modules.Multitenancy/Services/TenantExpiryScanJob.cs
index 6a19be0f30..a766ad16d5 100644
--- a/src/Modules/Multitenancy/Modules.Multitenancy/Services/TenantExpiryScanJob.cs
+++ b/src/Modules/Multitenancy/Modules.Multitenancy/Services/TenantExpiryScanJob.cs
@@ -84,7 +84,7 @@ public async Task RunAsync(CancellationToken cancellationToken)
     private async Task<bool> TryNotifyAsync(AppTenantInfo tenant, DateTime now, CancellationToken ct)
     {
         var validUpto = tenant.ValidUpto;
-        var graceEnds = validUpto.AddDays(_options.GraceWindowDays);
+        var graceEnds = validUpto.AddDays(_options.GracePeriodDays);
 
         string noticeType;
         if (now > graceEnds)
diff --git a/src/Modules/Multitenancy/Modules.Multitenancy/Services/TenantService.cs b/src/Modules/Multitenancy/Modules.Multitenancy/Services/TenantService.cs
index e1e81027a9..15d8fdbe01 100644
--- a/src/Modules/Multitenancy/Modules.Multitenancy/Services/TenantService.cs
+++ b/src/Modules/Multitenancy/Modules.Multitenancy/Services/TenantService.cs
@@ -166,7 +166,7 @@ public async Task<TenantStatusDto> GetStatusAsync(string id, CancellationToken c
     {
         var tenant = await GetTenantInfoAsync(id, cancellationToken).ConfigureAwait(false);
 
-        var graceEnds = tenant.ValidUpto.AddDays(_billingOptions.GraceWindowDays);
+        var graceEnds = tenant.ValidUpto.AddDays(_billingOptions.GracePeriodDays);
         var now = _timeProvider.GetUtcNow().UtcDateTime;
         string expiryState;
         if (now <= tenant.ValidUpto)
diff --git a/src/Modules/Multitenancy/Modules.Multitenancy/TenantBillingOptions.cs b/src/Modules/Multitenancy/Modules.Multitenancy/TenantBillingOptions.cs
index b3e54ebe16..a602706405 100644
--- a/src/Modules/Multitenancy/Modules.Multitenancy/TenantBillingOptions.cs
+++ b/src/Modules/Multitenancy/Modules.Multitenancy/TenantBillingOptions.cs
@@ -13,7 +13,7 @@ public sealed class TenantBillingOptions
     public string DefaultPlanKey { get; set; } = "free";
 
     /// <summary>Days past <c>ValidUpto</c> during which requests/logins still succeed.</summary>
-    public int GraceWindowDays { get; set; } = 7;
+    public int GracePeriodDays { get; set; } = 7;
 
     /// <summary>How many days before <c>ValidUpto</c> the daily scan starts sending "nearing expiry" reminders.</summary>
     public int ExpiryNotificationLeadDays { get; set; } = 7;
diff --git a/src/Tests/Integration.Tests/Tests/Multitenancy/AdjustTenantValidityTests.cs b/src/Tests/Integration.Tests/Tests/Multitenancy/AdjustTenantValidityTests.cs
index 11f33f64de..6f573ebb9e 100644
--- a/src/Tests/Integration.Tests/Tests/Multitenancy/AdjustTenantValidityTests.cs
+++ b/src/Tests/Integration.Tests/Tests/Multitenancy/AdjustTenantValidityTests.cs
@@ -69,7 +69,7 @@ public async Task AdjustValidity_Should_Allow_Backdating_ToExpireImmediately()
         var planKey = await CreatePlanAsync(rootClient, $"adj-b-{unique}", monthlyBasePrice: 10m);
         await CreateTenantAsync(rootClient, tenantId, $"adj-back-{unique}@tenant.com", planKey);
 
-        // Backdate well past the grace window — renewal would reject this; the override allows it.
+        // Backdate well past the grace period — renewal would reject this; the override allows it.
         var target = DateTime.UtcNow.AddDays(-30);
         var response = await rootClient.PostAsJsonAsync(
             $"{TestConstants.TenantsBasePath}/{tenantId}/adjust-validity",
diff --git a/src/Tests/Integration.Tests/Tests/Multitenancy/TenantExpiryEnforcementTests.cs b/src/Tests/Integration.Tests/Tests/Multitenancy/TenantExpiryEnforcementTests.cs
index 09eef0b959..0f218983d1 100644
--- a/src/Tests/Integration.Tests/Tests/Multitenancy/TenantExpiryEnforcementTests.cs
+++ b/src/Tests/Integration.Tests/Tests/Multitenancy/TenantExpiryEnforcementTests.cs
@@ -9,7 +9,7 @@ namespace Integration.Tests.Tests.Multitenancy;
 
 /// <summary>
 /// Verifies subscription-expiry enforcement in the post-auth tenant guard: a tenant past
-/// <c>ValidUpto</c> but within the grace window still passes (so requests/logins keep working during
+/// <c>ValidUpto</c> but within the grace period still passes (so requests/logins keep working during
 /// dunning), while a tenant past <c>ValidUpto + grace</c> is hard-blocked with 403 — mirroring the
 /// deactivation guard. Grace defaults to 7 days.
 /// </summary>
@@ -33,7 +33,7 @@ public async Task ExpiredTenant_PastGrace_Should_Be_Blocked()
         // While valid, the guard does not short-circuit — the token handler runs and fails on creds.
         (await TryIssueTokenAsync(tenantId)).ShouldNotBe(HttpStatusCode.Forbidden);
 
-        // Lapse well past the 7-day grace window.
+        // Lapse well past the 7-day grace period.
         await SetTenantValidityAsync(tenantId, DateTime.UtcNow.AddDays(-30));
 
         (await TryIssueTokenAsync(tenantId)).ShouldBe(HttpStatusCode.Forbidden,
@@ -45,11 +45,11 @@ public async Task LapsedTenant_WithinGrace_Should_Not_Be_Blocked()
     {
         var tenantId = await CreateTenantAsync();
 
-        // One day past expiry is still inside the 7-day grace window.
+        // One day past expiry is still inside the 7-day grace period.
         await SetTenantValidityAsync(tenantId, DateTime.UtcNow.AddDays(-1));
 
         (await TryIssueTokenAsync(tenantId)).ShouldNotBe(HttpStatusCode.Forbidden,
-            "a lapsed tenant within the grace window must still be allowed through the guard");
+            "a lapsed tenant within the grace period must still be allowed through the guard");
     }
 
     [Fact]
@@ -57,13 +57,13 @@ public async Task LapsedTenant_WithinGrace_Should_Emit_GraceHeader()
     {
         var tenantId = await CreateTenantAsync();
 
-        // One day past expiry — inside the 7-day grace window.
+        // One day past expiry — inside the 7-day grace period.
         await SetTenantValidityAsync(tenantId, DateTime.UtcNow.AddDays(-1));
 
         var (status, grace) = await ProbeAsync(tenantId);
 
         status.ShouldNotBe(HttpStatusCode.Forbidden);
-        grace.ShouldNotBeNull("a tenant in the grace window must receive the X-Subscription-Grace header");
+        grace.ShouldNotBeNull("a tenant in the grace period must receive the X-Subscription-Grace header");
         int.Parse(grace!, CultureInfo.InvariantCulture).ShouldBeInRange(1, 7);
     }
 
diff --git a/src/Tests/Integration.Tests/Tests/Multitenancy/TenantExpiryScanJobTests.cs b/src/Tests/Integration.Tests/Tests/Multitenancy/TenantExpiryScanJobTests.cs
index 05570011af..81618be68f 100644
--- a/src/Tests/Integration.Tests/Tests/Multitenancy/TenantExpiryScanJobTests.cs
+++ b/src/Tests/Integration.Tests/Tests/Multitenancy/TenantExpiryScanJobTests.cs
@@ -37,7 +37,7 @@ public async Task ScanJob_Should_Record_GraceNotice_Dedup_And_Email()
         var planKey = await CreatePlanAsync(rootClient, $"scan-m-{unique}", 10m);
         await CreateTenantAsync(rootClient, tenantId, adminEmail, planKey);
 
-        // Lapse into the grace window (1 day past ValidUpto).
+        // Lapse into the grace period (1 day past ValidUpto).
         var adjust = await rootClient.PostAsJsonAsync(
             $"{TestConstants.TenantsBasePath}/{tenantId}/adjust-validity",
             new { tenantId, validUpto = DateTime.UtcNow.AddDays(-1) });
diff --git a/src/Tests/Multitenancy.Tests/Services/TenantServiceStatusBoundaryTests.cs b/src/Tests/Multitenancy.Tests/Services/TenantServiceStatusBoundaryTests.cs
index 8a89ce7480..0e2b4c6c05 100644
--- a/src/Tests/Multitenancy.Tests/Services/TenantServiceStatusBoundaryTests.cs
+++ b/src/Tests/Multitenancy.Tests/Services/TenantServiceStatusBoundaryTests.cs
@@ -12,7 +12,7 @@ namespace Multitenancy.Tests.Services;
 /// <summary>
 /// Pins the expiry-state transitions in <see cref="TenantService.GetStatusAsync"/> exactly at the
 /// ValidUpto and grace-window boundaries, so the Active → InGrace → Expired badges never drift.
-/// Grace window is fixed at 7 days for these cases.
+/// Grace period is fixed at 7 days for these cases.
 /// </summary>
 public sealed class TenantServiceStatusBoundaryTests
 {
@@ -47,7 +47,7 @@ public async Task GetStatusAsync_Should_ResolveExpiryState_AtBoundary(double off
             dbContext: null!,
             provisioningService: null!,
             _clock,
-            Options.Create(new TenantBillingOptions { GraceWindowDays = GraceDays }),
+            Options.Create(new TenantBillingOptions { GracePeriodDays = GraceDays }),
             NullLogger<TenantService>.Instance);
 
         var status = await sut.GetStatusAsync(tenantId, CancellationToken.None);