How to Integrate the SRB API with Your POS Software

Step 1 — Store your SRB credentials

SRB issues its own credential set. In TaxBridge you enter it once on the Authorities / Credentials form, which renders exactly the fields SRB needs:

pos_user and pos_pass — SRB authenticates with these inside the request body, not with a Bearer token.

Credentials are AES-256-GCM encrypted at rest and never returned to your app. Don't have production credentials yet? Turn on Use simulator (sandbox) and build your whole integration first — see how to test tax APIs.

Step 2 — Create an API key

Generate a key scoped to the test environment (and optionally pinned to SRB). The full key — tbk_test_... — is shown once and stored only as a SHA-256 hash. Keep it as a secret; a lost key is regenerated, not recovered.

Step 3 — POST your first SRB invoice

Send your canonical invoice to POST /api/v1/invoices with the SRB header and an Idempotency-Key:

curl -X POST https://taxbridge.themetasum.com/api/v1/invoices \
  -H "Authorization: Bearer tbk_test_9f3a21c7b4d6e8f0_..." \
  -H "Content-Type: application/json" \
  -H "Idempotency-Key: 0b6d1c4e-7f9a-4a51-8d3c-2e5f7a91b204" \
  -H "X-Tax-Authority: SRB" \
  -d '{
    "invoiceNumber": "INV-10001",
    "invoiceDate": "2026-08-10T10:30:00",
    "invoiceType": "Sale",
    "currency": "PKR",
    "paymentMode": "Cash",
    "customer": { "name": "Walk-in Customer" },
    "items": [{
      "description": "Chicken Karahi Full", "hsCode": "11001010",
      "quantity": 1, "unitPrice": 1500.00,
      "taxRate": 16, "taxAmount": 240.00, "total": 1740.00
    }],
    "subTotal": 1500.00, "tax": 240.00, "total": 1740.00
  }'

Print the returned qrCode on the receipt and store the submissionId so you can query status later.

The SRB quirk TaxBridge handles for you

One gateway serves both Test and Live. The environment is chosen by a flag (Test | Live), not by a different URL — so an API key’s environment, not the URL, is what keeps a sandbox test from filing a real invoice.

Step 4 — Go to production

Once your sandbox flow is verified, complete company and branch configuration, store your production credentials and generate a tbk_live_ key. Sandbox and production stay completely separate — a sandbox key never files a real SRB invoice. See production onboarding.

Frequently asked questions