Magento B2B – Company, Shared Catalog, Negotiable Quote, custom plugins

Magento B2B is a separate module suite for business-to-business selling. Company accounts, Shared Catalogs with customer-specific pricing, Negotiable Quotes, and Requisition Lists are the core features. I show the architecture, how each feature connects to the core Magento data model, and how to extend them with custom plugins.

B2B module architecture

Company – the foundation of B2B

<?php

declare(strict_types=1);

use Magento\Company\Api\CompanyRepositoryInterface;
use Magento\Company\Api\Data\CompanyInterface;

class CompanyService
{
    public function __construct(
        private CompanyRepositoryInterface $companyRepository,
        private \Magento\Company\Api\CompanyManagementInterface $companyManagement,
        private \Magento\Framework\Api\SearchCriteriaBuilder $searchCriteriaBuilder
    ) {}

    public function getCompanyByCustomer(int $customerId): ?CompanyInterface
    {
        // Each customer can belong to one company
        return $this->companyManagement->getByCustomerId($customerId);
    }

    public function getCreditLimit(int $customerId): float
    {
        $company = $this->getCompanyByCustomer($customerId);
        if ($company === null) return 0.0;

        $credit = $company->getExtensionAttributes()?->getCompanyCredit();
        return (float) ($credit?->getCreditLimit() ?? 0.0);
    }

    public function getCompaniesWithLowCredit(float $threshold): array
    {
        $sc = $this->searchCriteriaBuilder->create();
        $companies = $this->companyRepository->getList($sc)->getItems();

        return array_filter($companies, function($company) use ($threshold) {
            $credit = $company->getExtensionAttributes()?->getCompanyCredit();
            $available = ($credit?->getCreditLimit() ?? 0) - ($credit?->getBalance() ?? 0);
            return $available < $threshold;
        });
    }
}

Shared Catalog - customer-specific pricing and visibility

<?php

declare(strict_types=1);

use Magento\SharedCatalog\Api\SharedCatalogRepositoryInterface;
use Magento\SharedCatalog\Api\ProductManagementInterface;
use Magento\SharedCatalog\Api\PriceManagementInterface;

class SharedCatalogService
{
    public function __construct(
        private SharedCatalogRepositoryInterface $sharedCatalogRepository,
        private ProductManagementInterface $productManagement,
        private PriceManagementInterface $priceManagement,
        private \Magento\Framework\Api\SearchCriteriaBuilder $searchCriteriaBuilder
    ) {}

    // Assign products to a shared catalog
    public function assignProducts(int $catalogId, array $skus): void
    {
        $catalog  = $this->sharedCatalogRepository->get($catalogId);
        $products = array_map(fn($sku) => $this->buildProductPayload($sku), $skus);

        $this->productManagement->assignProducts($catalog, $products);
    }

    // Set custom tier prices for a shared catalog
    public function setCustomPrices(int $catalogId, array $priceData): void
    {
        // priceData: [['sku' => 'SKU-001', 'price' => 29.99], ...]
        $catalog = $this->sharedCatalogRepository->get($catalogId);

        $tierPrices = array_map(fn($item) => [
            'price_type' => 'fixed',
            'website_id' => 0,
            'sku'        => $item['sku'],
            'qty'        => 1,
            'value'      => $item['price'],
            'customer_group_id' => $catalog->getCustomerGroupId(),
        ], $priceData);

        $this->priceManagement->saveStore($catalog, $tierPrices, []);
    }
}

Negotiable Quote - B2B pricing workflow

<?php

declare(strict_types=1);

use Magento\NegotiableQuote\Api\NegotiableQuoteRepositoryInterface;
use Magento\NegotiableQuote\Api\NegotiableQuoteManagementInterface;

class NegotiableQuoteService
{
    public function __construct(
        private NegotiableQuoteRepositoryInterface $quoteRepository,
        private NegotiableQuoteManagementInterface $quoteManagement
    ) {}

    // Apply custom discount to a negotiable quote
    public function applyDiscount(int $quoteId, float $discountPercent, string $note): void
    {
        $quote = $this->quoteRepository->getById($quoteId);
        $negotiableQuote = $quote->getExtensionAttributes()?->getNegotiableQuote();

        if ($negotiableQuote === null) {
            throw new \RuntimeException("Quote {$quoteId} is not negotiable");
        }

        // Set discount
        $negotiableQuote->setNegotiatedPriceType(
            \Magento\NegotiableQuote\Api\Data\NegotiableQuoteInterface::NEGOTIATED_PRICE_TYPE_PERCENTAGE_DISCOUNT
        );
        $negotiableQuote->setNegotiatedPriceValue($discountPercent);
        $negotiableQuote->setComments($note);
        $negotiableQuote->setStatus(
            \Magento\NegotiableQuote\Api\Data\NegotiableQuoteInterface::STATUS_SUBMITTED_BY_ADMIN
        );

        $this->quoteManagement->saveByCustomer($quote, $negotiableQuote);
    }
}

Custom plugin - block order if over credit limit

<?php

declare(strict_types=1);

namespace Vendor\B2bExtension\Plugin;

class CreditLimitOrderPlugin
{
    public function __construct(
        private \Magento\Company\Api\CompanyManagementInterface $companyManagement,
        private \Psr\Log\LoggerInterface $logger
    ) {}

    public function beforePlace(
        \Magento\Sales\Api\OrderManagementInterface $subject,
        \Magento\Sales\Api\Data\OrderInterface $order
    ): array {
        $customerId = (int) $order->getCustomerId();
        if ($customerId === 0) return [$order]; // guest checkout

        $company = $this->companyManagement->getByCustomerId($customerId);
        if ($company === null) return [$order]; // not a B2B customer

        $credit    = $company->getExtensionAttributes()?->getCompanyCredit();
        $limit     = (float) ($credit?->getCreditLimit() ?? PHP_FLOAT_MAX);
        $balance   = (float) ($credit?->getBalance() ?? 0.0);
        $available = $limit - $balance;

        if ($order->getGrandTotal() > $available) {
            throw new \Magento\Framework\Exception\LocalizedException(
                __('Order total exceeds your available credit limit of %1.', number_format($available, 2))
            );
        }

        return [$order];
    }
}

Summary

Magento B2B is a powerful but complex suite. Company accounts create the organisational structure; Shared Catalogs control what each company sees and at what price; Negotiable Quotes enable the sales rep workflow. Custom extensions via plugins follow the same patterns as regular Magento development - the B2B interfaces are well-defined and injectable. The credit limit plugin example shows how to intercept order placement to enforce B2B-specific business rules.