diff --git a/src/modules/sales/sales-invoices/dto/sales-invoice.dto.ts b/src/modules/sales/sales-invoices/dto/sales-invoice.dto.ts
index 82da22b..000b411 100644
--- a/src/modules/sales/sales-invoices/dto/sales-invoice.dto.ts
+++ b/src/modules/sales/sales-invoices/dto/sales-invoice.dto.ts
@@ -1,8 +1,9 @@
 import { ApiProperty, ApiPropertyOptional } from '@nestjs/swagger';
-import { Type } from 'class-transformer';
+import { Transform, Type } from 'class-transformer';
 import {
   ArrayNotEmpty,
   IsArray,
+  IsBoolean,
   IsIn,
   IsNotEmpty,
   IsOptional,
@@ -230,6 +231,12 @@ export class ListSalesInvoicesQueryDto extends PaginationQueryDto {
   @IsOptional()
   @IsString()
   search?: string;
+
+  @ApiPropertyOptional()
+  @IsOptional()
+  @Transform(({ value }) => value === true || value === 'true')
+  @IsBoolean()
+  payable?: boolean;
 }
 
 export class SalesInvoiceDto {
diff --git a/src/modules/sales/sales-invoices/sales-invoice.ts b/src/modules/sales/sales-invoices/sales-invoice.ts
index 18fb3bc..f7b3798 100644
--- a/src/modules/sales/sales-invoices/sales-invoice.ts
+++ b/src/modules/sales/sales-invoices/sales-invoice.ts
@@ -94,6 +94,7 @@ export type ListSalesInvoicesFilters = {
   readonly salesOrderId?: string;
   readonly packingSlipId?: string;
   readonly search?: string;
+  readonly payable?: boolean;
   readonly orderBy?: string;
   readonly orderType?: string;
   readonly limit: number;
diff --git a/src/modules/sales/sales-invoices/sales-invoices.repository.ts b/src/modules/sales/sales-invoices/sales-invoices.repository.ts
index cff176e..2a222f8 100644
--- a/src/modules/sales/sales-invoices/sales-invoices.repository.ts
+++ b/src/modules/sales/sales-invoices/sales-invoices.repository.ts
@@ -4,7 +4,7 @@ import {
   Injectable,
   NotFoundException,
 } from '@nestjs/common';
-import { and, asc, count, eq, ilike, inArray, or, SQL, sum } from 'drizzle-orm';
+import { and, asc, count, eq, gt, ilike, inArray, or, SQL, sum } from 'drizzle-orm';
 import { toOrderClauses } from '../../../common/http/response';
 import {
   catalogRelationFromMap,
@@ -31,7 +31,10 @@ import {
 } from '../../../database/sales-payments-table';
 import { DocumentCodeService } from '../shared/document-code.service';
 import { DOCUMENT_PREFIXES } from '../shared/document-prefixes';
-import { SALES_INVOICE_STATUSES } from '../shared/sales-fields';
+import {
+  PAYABLE_INVOICE_STATUSES,
+  SALES_INVOICE_STATUSES,
+} from '../shared/sales-fields';
 import type {
   CreateSalesInvoiceInput,
   ListSalesInvoicesFilters,
@@ -393,6 +396,10 @@ export class SalesInvoicesRepository {
         parts.push(search);
       }
     }
+    if (filters.payable) {
+      parts.push(inArray(salesInvoices.status, [...PAYABLE_INVOICE_STATUSES]));
+      parts.push(gt(salesInvoices.balance, '0'));
+    }
     if (parts.length === 0) {
       return undefined;
     }
diff --git a/src/modules/sales/sales-invoices/sales-invoices.service.spec.ts b/src/modules/sales/sales-invoices/sales-invoices.service.spec.ts
index 574c212..9e3aabc 100644
--- a/src/modules/sales/sales-invoices/sales-invoices.service.spec.ts
+++ b/src/modules/sales/sales-invoices/sales-invoices.service.spec.ts
@@ -191,6 +191,36 @@ describe('SalesInvoicesService', () => {
     ).rejects.toBeInstanceOf(BadRequestException);
   });
 
+  it('updateStatus allows draft to processed even when sourced from a sales order', async () => {
+    repository.findById.mockResolvedValue({
+      ...sample,
+      salesOrderId: 'so-1',
+    });
+    repository.updateStatus.mockResolvedValue({
+      ...sample,
+      salesOrderId: 'so-1',
+      status: Status.create('processed', SALES_INVOICE_STATUSES),
+    });
+    const result = await service.updateStatus('si-1', 'processed', 'user-1');
+    expect(repository.updateStatus).toHaveBeenCalledWith(
+      'si-1',
+      expect.objectContaining({ value: 'processed' }),
+      'user-1',
+    );
+    expect(result.status).toBe('processed');
+  });
+
+  it('updateStatus rejects processed to completed as a user transition', async () => {
+    repository.findById.mockResolvedValue({
+      ...sample,
+      status: Status.create('processed', SALES_INVOICE_STATUSES),
+    });
+    await expect(
+      service.updateStatus('si-1', 'completed', 'user-1'),
+    ).rejects.toBeInstanceOf(BadRequestException);
+    expect(repository.updateStatus).not.toHaveBeenCalled();
+  });
+
   it('applyPaymentEffects sets partial when underpaid', async () => {
     repository.findById.mockResolvedValue(sample);
     repository.computeTotals.mockResolvedValue({
diff --git a/src/modules/sales/sales-invoices/sales-invoices.service.ts b/src/modules/sales/sales-invoices/sales-invoices.service.ts
index 840c36b..efbee88 100644
--- a/src/modules/sales/sales-invoices/sales-invoices.service.ts
+++ b/src/modules/sales/sales-invoices/sales-invoices.service.ts
@@ -57,6 +57,7 @@ export type ListSalesInvoicesQuery = {
   readonly salesOrderId?: string;
   readonly packingSlipId?: string;
   readonly search?: string;
+  readonly payable?: boolean;
   readonly orderBy?: string;
   readonly orderType?: string;
   readonly page?: number;
@@ -103,6 +104,7 @@ export class SalesInvoicesService {
       salesOrderId: query.salesOrderId,
       packingSlipId: query.packingSlipId,
       search: query.search,
+      payable: query.payable,
       orderBy: query.orderBy,
       orderType: query.orderType,
       limit: page.limit,
@@ -215,7 +217,6 @@ export class SalesInvoicesService {
     }
     const status = this.assertStatus(statusRaw);
     if (
-      current.salesOrderId ||
       !isAllowedStatusTransition(
         current.status.value,
         status.value,
diff --git a/src/modules/sales/sales-payments/sales-payments.service.spec.ts b/src/modules/sales/sales-payments/sales-payments.service.spec.ts
index 5a713b9..698d60e 100644
--- a/src/modules/sales/sales-payments/sales-payments.service.spec.ts
+++ b/src/modules/sales/sales-payments/sales-payments.service.spec.ts
@@ -67,7 +67,11 @@ describe('SalesPaymentsService', () => {
 
   beforeEach(async () => {
     jest.clearAllMocks();
-    salesInvoicesService.findById.mockResolvedValue({ id: 'si-1' });
+    salesInvoicesService.findById.mockResolvedValue({
+      id: 'si-1',
+      status: 'processed',
+      balance: '25000.0000',
+    });
     const moduleRef: TestingModule = await Test.createTestingModule({
       providers: [
         SalesPaymentsService,
@@ -92,6 +96,38 @@ describe('SalesPaymentsService', () => {
     expect(arg.invoices[0]?.amount.value).toBe('10000.0000');
   });
 
+  it('create rejects a draft invoice allocation', async () => {
+    salesInvoicesService.findById.mockResolvedValue({
+      id: 'si-1',
+      status: 'draft',
+      balance: '25000.0000',
+    });
+    await expect(
+      service.create({
+        date: '2026-08-24T10:00:00+07:00',
+        invoices: [{ invoiceId: 'si-1', amount: '10000' }],
+        userId: 'user-1',
+      }),
+    ).rejects.toBeInstanceOf(BadRequestException);
+    expect(repository.create).not.toHaveBeenCalled();
+  });
+
+  it('create rejects an invoice with no remaining balance', async () => {
+    salesInvoicesService.findById.mockResolvedValue({
+      id: 'si-1',
+      status: 'processed',
+      balance: '0.0000',
+    });
+    await expect(
+      service.create({
+        date: '2026-08-24T10:00:00+07:00',
+        invoices: [{ invoiceId: 'si-1', amount: '10000' }],
+        userId: 'user-1',
+      }),
+    ).rejects.toBeInstanceOf(BadRequestException);
+    expect(repository.create).not.toHaveBeenCalled();
+  });
+
   it('update rejects status on PATCH', async () => {
     await expect(
       service.update('sp-1', { status: 'approved', userId: 'user-1' }),
diff --git a/src/modules/sales/sales-payments/sales-payments.service.ts b/src/modules/sales/sales-payments/sales-payments.service.ts
index bb110c1..bf2515b 100644
--- a/src/modules/sales/sales-payments/sales-payments.service.ts
+++ b/src/modules/sales/sales-payments/sales-payments.service.ts
@@ -22,6 +22,7 @@ import {
   isValidImageUrl,
   isAllowedStatusTransition,
   parseCsvRecord,
+  PAYABLE_INVOICE_STATUSES,
   SALES_PAYMENT_STATUSES,
   SALES_PAYMENT_USER_TRANSITIONS,
 } from '../shared/sales-fields';
@@ -341,7 +342,8 @@ export class SalesPaymentsService {
     }
     const result: SalesPaymentAllocationInput[] = [];
     for (const line of lines) {
-      await this.salesInvoicesService.findById(line.invoiceId);
+      const invoice = await this.salesInvoicesService.findById(line.invoiceId);
+      this.assertInvoicePayable(invoice);
       const amount = this.parseDecimal(line.amount);
       if (!amount.isPositive()) {
         throw new BadRequestException('Invalid amount');
@@ -351,6 +353,28 @@ export class SalesPaymentsService {
     return result;
   }
 
+  private assertInvoicePayable(invoice: {
+    status?: string;
+    balance?: string;
+  }): void {
+    if (
+      !invoice.status ||
+      !(PAYABLE_INVOICE_STATUSES as readonly string[]).includes(invoice.status)
+    ) {
+      throw new BadRequestException('Invoice is not payable');
+    }
+    try {
+      if (!Decimal.create(invoice.balance ?? '0').isPositive()) {
+        throw new BadRequestException('Invoice is not payable');
+      }
+    } catch (error) {
+      if (error instanceof InvalidDecimalError) {
+        throw new BadRequestException('Invoice is not payable');
+      }
+      throw error;
+    }
+  }
+
   private assertImage(image: SalesImageBody): SalesPaymentImageInput {
     if (!isValidImageUrl(image.url)) {
       throw new BadRequestException('Invalid image URL');
diff --git a/src/modules/sales/shared/sales-fields.spec.ts b/src/modules/sales/shared/sales-fields.spec.ts
index c551bae..871b476 100644
--- a/src/modules/sales/shared/sales-fields.spec.ts
+++ b/src/modules/sales/shared/sales-fields.spec.ts
@@ -77,14 +77,14 @@ describe('sales fields', () => {
     ).toBe(false);
   });
 
-  it('limits invoice user transitions to cancelled', () => {
+  it('allows invoice user transitions from draft to processed or cancelled', () => {
     expect(
       isAllowedStatusTransition(
         'draft',
         'processed',
         SALES_INVOICE_USER_TRANSITIONS,
       ),
-    ).toBe(false);
+    ).toBe(true);
     expect(
       isAllowedStatusTransition(
         'draft',
@@ -92,6 +92,13 @@ describe('sales fields', () => {
         SALES_INVOICE_USER_TRANSITIONS,
       ),
     ).toBe(true);
+    expect(
+      isAllowedStatusTransition(
+        'processed',
+        'completed',
+        SALES_INVOICE_USER_TRANSITIONS,
+      ),
+    ).toBe(false);
   });
 
   it('allows payment pending to approved, rejected, or draft', () => {
diff --git a/src/modules/sales/shared/sales-fields.ts b/src/modules/sales/shared/sales-fields.ts
index ae42549..2fbbb20 100644
--- a/src/modules/sales/shared/sales-fields.ts
+++ b/src/modules/sales/shared/sales-fields.ts
@@ -69,13 +69,15 @@ export const PACKING_SLIP_USER_TRANSITIONS: Record<string, readonly string[]> =
 
 export const SALES_INVOICE_USER_TRANSITIONS: Record<string, readonly string[]> =
   {
-    draft: ['cancelled'],
+    draft: ['processed', 'cancelled'],
     processed: ['cancelled'],
     partial: ['cancelled'],
     completed: ['cancelled'],
     cancelled: [],
   };
 
+export const PAYABLE_INVOICE_STATUSES = ['processed', 'partial'] as const;
+
 export const SALES_PAYMENT_USER_TRANSITIONS: Record<string, readonly string[]> =
   {
     draft: ['pending'],
diff --git a/test/sales-invoices.e2e-spec.ts b/test/sales-invoices.e2e-spec.ts
index 494ecdf..9e959f0 100644
--- a/test/sales-invoices.e2e-spec.ts
+++ b/test/sales-invoices.e2e-spec.ts
@@ -181,6 +181,12 @@ describe('Sales invoices (e2e)', () => {
       .send({ status: 'processed' })
       .expect(400);
 
+    await request(app.getHttpServer())
+      .patch(`/sales-invoices/${id}/status`)
+      .set('Authorization', `Bearer ${token}`)
+      .send({ status: 'processed' })
+      .expect(200);
+
     await request(app.getHttpServer())
       .delete(`/sales-invoices/${id}`)
       .set('Authorization', `Bearer ${token}`)
diff --git a/test/sales-payments.e2e-spec.ts b/test/sales-payments.e2e-spec.ts
index 80d48ef..ad80d11 100644
--- a/test/sales-payments.e2e-spec.ts
+++ b/test/sales-payments.e2e-spec.ts
@@ -147,6 +147,11 @@ describe('Sales payments (e2e)', () => {
       })
       .expect(201);
     invoiceId = (invoice.body as { id: string }).id;
+    await request(app.getHttpServer())
+      .patch(`/sales-invoices/${invoiceId}/status`)
+      .set(auth)
+      .send({ status: 'processed' })
+      .expect(200);
   });
 
   afterAll(async () => {
@@ -182,6 +187,12 @@ describe('Sales payments (e2e)', () => {
       .send({ status: 'approved' })
       .expect(400);
 
+    await request(app.getHttpServer())
+      .patch(`/sales-payments/${id}/status`)
+      .set('Authorization', `Bearer ${token}`)
+      .send({ status: 'pending' })
+      .expect(200);
+
     await request(app.getHttpServer())
       .patch(`/sales-payments/${id}/status`)
       .set('Authorization', `Bearer ${token}`)