Most people meet Bacs without being told its name. Your salary arrives on it. So does a refund that takes an oddly specific three days. Then a solicitor asks for a CHAPS payment on completion day and suddenly the UK has three different bank transfer systems, each with its own clock, and nobody has explained which is which.
Bacs stands for Bankers Automated Clearing System, an expansion gov.uk still spells out on its own payment pages. It is the oldest of the three rails, the slowest, the cheapest, and the one carrying the most predictable money in the country. The three-working-day wait it is famous for is not a queue. It is the design.
Which rail moves your money, and how fast
HMRC publishes the plainest side-by-side comparison in British public life, because it accepts payment on all three and has to tell people when the money will land.
| Rail | When it arrives at HMRC | Runs on |
|---|---|---|
| Faster Payments | Same or next day, including weekends and bank holidays | Deferred net settlement |
| CHAPS | Same working day, if you pay within your bank’s processing times | Real-time gross settlement |
| Bacs | 3 working days | Deferred net settlement |
Source: GOV.UK guidance on paying HMRC by bank transfer, read 1 September 2026.
That table is the practical answer, and for most payments it is the only answer you need. What follows is why the three numbers are so different, because the reason changes how you should think about deadlines.
Why Bacs takes three days
The Bank of England settles UK payment systems through its Real-Time Gross Settlement infrastructure, and it supports more than one settlement model. Only CHAPS uses the real-time gross model, where each payment obligation between participants is settled individually, on a gross basis, throughout the business day.
Everything else, including Bacs and Faster Payments, uses net settlement. The Bank describes how that works: a net settlement system runs in regular cycles, and at the end of each cycle the operator works out each participant’s obligations on a multilateral net basis, so each one either owes or is owed a single figure. The operator then instructs the Bank to settle those single figures.
The Bank is also specific about the sequencing in the UK, and this is the bit that explains the three days. The norm here is deferred net settlement: the actual settlement happens after information on individual payments has been exchanged, and after customers have been debited and credited. Information moves first, cash between banks catches up afterwards.
HMRC’s internal manual states the consumer-facing consequence without dressing it up. A Bacs Direct Credit moves money electronically from one bank account to another on a specific date, is available only to organisations authorised to submit files directly to Bacs, and normally takes three bank working days to arrive. Bank working days means Monday to Friday, excluding bank holidays.
Two things follow. A payment submitted on a Friday is not landing before the middle of the next week. And bank holidays genuinely stop the clock rather than slowing it, which is why the days around Easter and Christmas produce a predictable wave of confusion every year.
The scale nobody sees
The Bank of England’s daily average settlement figures for 2024 show how the workload splits between the rails, and it is not what most people assume.
| System | Daily average settled in RTGS, 2024 |
|---|---|
| CHAPS | £344,409 million |
| Bacs, net | £5,265 million |
| Faster Payments, net | £1,929 million |
| All settlement services | £747,202 million |
CHAPS accounts for around 0.5% of total UK payment volumes but 92% of total sterling payment values. In 2024 it settled over £87 trillion, averaging over £344 billion every working day, across roughly 208,000 payments a day with an average payment value of £1.7 million.
The Bacs and Faster Payments figures look small next to that only because they are net. Millions of individual payments have already been offset against each other before a single number reaches the Bank. That netting is exactly what makes those rails cheap, and exactly what makes them slow.
CHAPS: the one with a clock on it
If Bacs is a cycle, CHAPS is an appointment, and the Bank of England publishes the timetable.
The system opens at 6am each working day. Participants must be open to receive by 8am and must send by 10am. It closes at 6pm for bank-to-bank payments, but customer payments must be submitted by 5.40pm. It runs Monday to Friday only, excluding bank and public holidays in England and Wales. There are over 35 direct participants, with several thousand other institutions accessing it indirectly through one of them.
Three features make it the property rail. Payments settle individually and in real time on the same day they are submitted. The transfer is irrevocable between direct participants. And there is no minimum or maximum payment limit, which is the single most important line for anyone moving a completion sum.
The Bank names the uses directly: financial institutions settling money market and foreign exchange trades, corporates making high-value time-sensitive payments, solicitors and conveyancers completing property transactions, and individuals buying high-value items such as a car or paying a deposit on a house.
There is a protection detail worth knowing. The Bank has set a maximum reimbursement level of £85,000 per claim for authorised push payment scams on UK retail CHAPS payments, aligning with the equivalent limit the Payment Systems Regulator set for Faster Payments. Above that figure you are relying on your own diligence, which is why solicitors are so insistent about verifying account details by phone.
What it costs
Bacs and Faster Payments are normally free to a personal customer. CHAPS is not, and the Bank of England quotes the Payment Systems Regulator’s 2015 finding: indirect participants typically paid around £2 to £3 per CHAPS payment, capped at £30, while end users typically paid between £25 and £30.
That gap is the entire decision. Twenty-five pounds is absurd on a £200 transfer and irrelevant on a £280,000 completion payment where a missed deadline costs you the day.
Choosing, in one line each
Paying a person, any everyday amount. Faster Payments, which is what your banking app uses by default. Same or next day, weekends included.
Receiving a salary, a pension, or a regulated refund. Bacs, and you have no say in it. Build the three-day cycle into your planning rather than treating each instance as a delay. If your income lands on a Bacs schedule, a budget built around that arrival date is more robust than one built around the calendar month.
Setting up a recurring credit or debit. Bacs again, and the setup requires exact account details. Getting them from the wrong place is the usual failure, which is why knowing how to read the account identifiers on a cheque still matters.
Completing on a property, or any large payment with a fixed deadline. CHAPS, submitted well before the 5.40pm customer cut-off, on a working day. This is also the moment the underlying deal matters more than the transfer: the rate on the mortgage itself will cost or save multiples of the fee, and if you want certainty over a long horizon, a longer fixed term is the lever, not the payment method.
Paying someone abroad. Different territory again, and the identifiers change. gov.uk asks for an IBAN and BIC for overseas payments to HMRC, so understanding what an IBAN encodes is the prerequisite rather than an optional extra.
The bit that catches people out
Money sitting between rails earns nothing, and on a three-day Bacs cycle that is three days a month across a year.
It matters most in the run-up to a large payment, when a deposit is sitting idle waiting for a completion date. Parking it somewhere it earns until the day it is needed is free money, provided the account allows withdrawal on demand. An easy-access account is the right shape for that, and the difference between the top of the market and a default current account is worth checking against what UK savings accounts are currently paying rather than assumed.
The rail determines when the money moves. Where it sits in between is still your decision, and it is the half of the payment mechanics that actually pays you something.