What is Modulus Checking?

Modulus checking is an industry-standard validation method used to verify that a UK sort code and account number combination is valid before processing a payment.

Our service uses the official BACS-approved modulus checking algorithms (Modulus 10 and Modulus 11) to mathematically verify that account details are correctly formatted and could represent a valid bank account.

Did you know?

Invalid payment details cost UK businesses over £800 million annually in failed transactions, administrative overhead, and customer service issues.

Key Benefits

Reduce Failed Payments
Catch invalid account details before submission
Improve User Experience
Provide instant feedback on data entry errors
Lower Operational Costs
Reduce manual intervention and customer support
BACS Compliant
Uses official modulus checking algorithms

How It Works

Simple integration, powerful validation

User Enters Details

Customer inputs sort code and account number in your payment form

API Call

Your system sends a validation request to our API endpoint

Validation

Our system applies modulus checking algorithms in under 100ms

Instant Result

Receive immediate validation result with detailed feedback

Simple RESTful API

Integrate in minutes with our developer-friendly API

curl -X GET "https://wsp.esortcode.com/uk/v1/validateaccount?key=YOUR_API_KEY&sortcode=200000&accountNumber=12345678"

const apiKey = 'YOUR_API_KEY';
const sortCode = '200000';
const accountNumber = '12345678';

const url = `https://wsp.esortcode.com/uk/v1/validateaccount?key=${apiKey}&sortcode=${sortCode}&accountNumber=${accountNumber}`;

const response = await fetch(url);
const result = await response.json();

import requests

api_key = 'YOUR_API_KEY'
sort_code = '200000'
account_number = '12345678'

url = f'https://wsp.esortcode.com/uk/v1/validateaccount?key={api_key}&sortcode={sort_code}&accountNumber={account_number}'

response = requests.get(url)
result = response.json()

$apiKey = 'YOUR_API_KEY';
$sortCode = '200000';
$accountNumber = '12345678';

$url = "https://wsp.esortcode.com/uk/v1/validateaccount?key={$apiKey}&sortcode={$sortCode}&accountNumber={$accountNumber}";

$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
$result = json_decode(curl_exec($ch), true);
curl_close($ch);

Response

{
  "modulusCheck": {
    "sortcode": "200000",
    "accountNumber": "12345678",
    "valid": true
  },
  "branches": [
    {
      "bankName": "BARCLAYS BANK PLC",
      "branchTitle": "Head Office",
      "address1": "1 Churchill Place",
      "town": "London",
      "postcode": "E14 5HP",
      "bacsPayments": true,
      "directDebits": true,
      "directCredits": true
    }
  ]
}

Transparent Pricing

Pay only for what you use. No hidden fees, no monthly minimums.

Calculate Your Price

Move the slider to see how much you'll save with volume pricing

Number of checks per month:

500 100,000

Credit Pack Size

500

checks

Price Per Check
4.0p
per validation

Total Cost

£20.00

one-time payment

You save: £0.00 compared to competitors

Credits never expire

No setup fees or monthly charges

Get Started Now

Includes 1,000 free checks to test our service

Volume Pricing Tiers

See how much you can save with higher volumes

500 checks

4.0p

£20.00

Baseline

1,000 checks

3.8p

£38.00

5% off

5,000 checks

3.4p

£170.00

15% off

10,000 checks

3.2p

£320.00

20% off

25,000 checks

2.9p

£725.00

27.5% off

50,000 checks

2.7p

£1,350.00

32.5% off

100,000 checks

2.5p

£2,500.00

37.5% off

100,000+ checks

Please Call for Custom Pricing

Enterprise Features Included

Everything you need for production-grade validation

Bank-Grade Security

TLS 1.3 encryption, SOC 2 compliance

Real-time Updates

Daily database updates for accuracy

Usage Analytics

Detailed dashboards and reporting

24/7 Support

Expert technical support team

Webhook Support

Real-time notifications and callbacks

Batch Processing

Validate hundreds of records at once

Modulus Checking