BACS (Bankers’ Automated Clearing Services) is the UK’s system for processing electronic payments between bank accounts. It handles two main types of transaction: Direct Credit (payments pushed by the payer) and Direct Debit (payments pulled by the payee). BACS processes billions of transactions annually, making it one of the foundational payment systems in UK commerce.
The two types of BACS transaction
Direct Credit
A Direct Credit is a payment initiated by the payer and sent to the recipient’s bank account. Common uses include:
- Payroll processing for salaries and wages
- Supplier payments for settled invoices
- Pension payments from employers or pension schemes
- Tax refunds from HMRC
- Dividend payments to shareholders
Direct Debit
A Direct Debit is a payment collected by the payee from the payer’s account, with the payer’s prior authorisation. For a comprehensive guide to direct debits, see what a direct debit is.
The three-day BACS cycle
All BACS transactions follow a three working day processing cycle:
| Day | Name | What happens |
|---|---|---|
| Day 1 | Input day | The originator submits the payment file to BACS |
| Day 2 | Processing day | BACS sorts and routes instructions to the correct banks |
| Day 3 | Entry day | Funds are debited from the payer’s account and credited to the recipient’s account |
Working day rules
- Only Monday to Friday count as working days (excluding bank holidays)
- A file submitted on Monday settles on Wednesday
- A file submitted on Wednesday settles on Friday
- A file submitted on Thursday settles on the following Monday
This three-day cycle is the key difference between BACS and Faster Payments, which settles in seconds. For time-sensitive payments, Faster Payments or CHAPS is more appropriate.
How businesses submit BACS payments
There are three main ways to submit BACS files:
1. Direct BACS submission
Larger organisations connect directly to the Bacstel-IP network using approved software. This requires:
- Registration as a BACS Service User with a Service User Number (SUN)
- Approved BACS software (e.g. Bottomline PTX, AccessPay, Bankline)
- A Bacstel-IP connection through an approved network
- Designated BACS operatives with smartcards for authentication
2. Through a BACS bureau
A BACS bureau is a third-party provider that submits BACS files on behalf of businesses. This is common for:
- Small and medium-sized businesses without direct connectivity
- Companies that outsource payroll processing
- Organisations that do not process enough volume to justify direct membership
3. Via bank platforms
Most UK business banks offer BACS submission through their online banking platforms. This is the simplest option for businesses with lower volumes, though it may have limitations on file sizes and formatting.
BACS for payroll
BACS Direct Credit is the standard method for paying UK employees. The process typically works as follows:
- Payroll team calculates net pay, tax deductions and pension contributions
- Payroll software generates a BACS file with payment instructions for all employees
- The file is submitted to BACS on the appropriate input day (three working days before payday)
- On payday (entry day), all employees receive their net pay
Payroll timing example
For a payday of Friday 28th, the BACS file must be submitted by Wednesday 26th (assuming no bank holidays). The timeline:
- Wednesday 26th: Input day (file submitted)
- Thursday 27th: Processing day
- Friday 28th: Entry day (employees paid)
Common payroll BACS mistakes
- Submitting the file too late, causing employees to be paid late
- Not accounting for bank holidays in the three-day cycle
- Incorrect sort codes or account numbers causing returned payments
- Not reconciling the BACS file total against the payroll total
BACS for supplier payments
Many UK businesses use BACS Direct Credit for regular supplier payments, particularly where:
- Payments are planned in advance with known payment terms
- Multiple suppliers need to be paid in a single batch
- The three-day processing time is acceptable
- Cost efficiency is important (BACS is cheaper per transaction than CHAPS)
Typical supplier payment workflow
- Invoices are received and matched to purchase orders
- Approved invoices are scheduled for payment based on their due dates
- A payment run is created grouping all invoices due on the same date
- The BACS file is generated and submitted three working days before the payment date
- On entry day, all suppliers receive payment simultaneously
Transaction limits and volumes
| Metric | Detail |
|---|---|
| Transaction limit | No per-transaction maximum |
| File size limit | Up to 1.2 million items per file |
| Daily volume | BACS processes approximately 20 million items per day |
| Annual volume | Over 6 billion transactions per year |
The absence of a per-transaction limit makes BACS suitable for high-value payments where same-day settlement is not required.
Costs
BACS is one of the most cost-effective UK payment methods:
| Submission method | Typical cost per item |
|---|---|
| Direct BACS (large volume) | £0.04 - £0.10 |
| BACS bureau | £0.10 - £0.50 |
| Bank platform (small volume) | £0.20 - £0.50 |
Compare this to CHAPS at £20-£35 per payment, and the cost advantage of BACS for bulk payments is clear.
BACS vs Faster Payments vs CHAPS
| Feature | BACS | Faster Payments | CHAPS |
|---|---|---|---|
| Speed | 3 working days | Seconds to 2 hours | Same day |
| Availability | Working days | 24/7/365 | Working days |
| Transaction limit | No limit | £1,000,000 | No limit |
| Cost | Very low | Usually free (personal) | £20 - £35 |
| Best for | Bulk payments, payroll | Urgent everyday transfers | High-value, time-critical |
| Batch processing | Yes | No (individual) | No (individual) |
For a comparison of the speed advantage, see Faster Payments. For high-value urgent payments, see CHAPS.
Returned and failed BACS payments
Payments can be returned for several reasons:
- Account closed at the receiving bank
- Invalid sort code or account number
- Deceased account holder
- Account transferred to a different bank
Returned items are reported back through the BACS system, typically on day 3 or shortly after. Businesses should have procedures to:
- Investigate the cause of the return
- Contact the intended recipient to obtain correct details
- Resubmit the corrected payment
- Update master data to prevent repeated failures
Accounting treatment
BACS Direct Credit (payment made)
Debit: Trade payables / Salary expense
Credit: Bank
BACS Direct Credit (payment received)
Debit: Bank
Credit: Trade receivables / Revenue
Timing considerations
Because of the three-day cycle, there can be a timing difference between when the payment is submitted and when it appears on the bank statement. At month-end, businesses may need to account for:
- Payments submitted but not yet settled (items in transit)
- Payments received on the bank statement but not yet reconciled in the ledger
These items should be included in the bank reconciliation to ensure accurate cash reporting.
Governance and regulation
BACS is operated by Pay.UK and governed by:
- Bacs Payment Scheme rules covering Direct Credit and Direct Debit
- Payment Services Regulations 2017 (PSD2 implementation)
- FCA oversight of payment system operators and participants
- Bank of England supervision of systemically important payment systems
Businesses using BACS must comply with these rules, including data protection requirements for handling customer bank details and maintaining adequate security for BACS submission credentials.
BACS in the context of UK payments
BACS remains essential to the UK payment landscape despite the growth of Faster Payments. Its strengths in bulk processing, cost efficiency and established infrastructure make it the natural choice for payroll, pension payments, direct debits and planned supplier payment runs where same-day settlement is not required.