back to top


Account Limit

A monetary limit set by the sponsor for a fixed period on an individual account to restrict the value of transactions.


Automated Clearing House


Automated Direct Debit Amendment and Cancellation Service Service - the Bacs service allowing banks or building societies to advise Direct Debit service users of any amendments to or cancellations to Direct Debit Instructions (DDIs). Also used to advise service users of the new bank account details when a customer transfers their account from one paying bank to another. The advice is sent either electronically or on paper.

Advance Notice

The notice period (normally 10 working days plus postal time) given to the payer in respect of the date of debiting and the amount to be debited.

Agency Bank

Any bank or building society that is not a member of Bacs.

Amalgamation of Payments

Multiple or combined payments relating to more than one contract collected under a single Direct Debit Instruction (DDI).


The Association for Payment Clearing Services manages the main clearing networks which allow UK banks and building societies to exchange payments.


Application Programmers Interface. An API allows programmers to integrate a service directly into their applications or websites. See also SOAP.


Automated Return of Unapplied Credits - a mechanism by which paying banks return unapplied credits to the service user via Bacs.


Automated Return of Unpaid Direct Debits - the automated system used by banks to return unpaid Direct Debit payments. Unpaid Direct Debits are advised to the originator by Bacs using the Automated Unpaid Direct Debit (AUDD) report.


Automated Direct Debit Instruction Service - the Bacs system for electronically lodging Direct Debit Instructions(DDIs).


For the purpose of AUDDIS the AUDDIS Direct Debit Instruction (DDI) is either the Instruction or any subsequent instruction from the customer to the originator amending the terms of the original AUDDIS DDI.


Advice of Wrong Account for Automated Credits Service - if a Bacs Direct Credit has incorrect account destination details, the receiving bank will try to locate the correct account and advise the originating organisation of the details. AWACS is the automated system used by banks to notify the organisation of the correct details to be used for future payments.

back to top



Bacs Approved Bureau - a commercial bureau awarded approved status by Bacs.


Bankers Automated Clearing Service. Bacs is a not for profit organisation owned by the leading banks and building societies in the UK. Bacs is responsible for the schemes behind the clearing and settlement of automated electronic payments in the UK.

Bacs Cycle

The three day cycle, minimum three English bank working days, taken for a payment instruction to be submitted to Bacs for processing and the time taken for the funds to reach the destination account. The processing cycle has the following stages: Day 1 – Input Day (Arrival at Bacs) Day 2 – Processing Day (Instructions processed by Bacs) Day 3 – Entry Day (Funds reach the destination bank)

Bacs Direct Credit

An electronic payment processed by Bacs and made directly to a bank or building society account.

Bacs Processing Calendar

Each year Bacs issue a calendar which shows the days which can be used for Bacs processing. If you do not want to miss an important deadline then can refer to the calendar to ensure you get the right input day.


See Bacstel-IP


Bacstel-IP is a service provided by Bacs for the transmission of Direct Debits and Direct Credits. The service replaced the old Bacstel service and uses an Internet Protocol (IP) and Public Key Infrastructure (PKI) for secure Electronic Funds Transfer (EFT). Only Bacs Approved software may access the service. Mosaic software is a Bacs Approved Solution Supplier (BASS. and it's Bacs Software can be used on the Bacstel-IP service.


A bank or building society.


Bacs Approved Solution Supplier – A software supplier that has been approved by Bacs to sell software that is capable of transmitting Bacs files. Becoming Bacs approved means that the software has to be tested by Bacs and is secure. Currently we are one of only eighteen approved suppliers.


Bank Identifier Code


A department or office of a financial institution, identified by a unique sort code.


An organisation that sends payments to Bacs on behalf of an organisation:
Commercial Bureau- submits data to Bacs on behalf of totally independent third party.
Bank Bureau - offers members services direct.
In house commercial group - works solely for the group and submits data to Bacs, incorporating either a single company that has different user numbers for different applications, or a company group where each individual company has its own user number.
Other - a bureau that is not in any of the above categories.

back to top


Calendar Day

A day in the Gregorian calendar, for example, 11 July 2015.


Clearing House Automated Payment System - a system providing same day settlement between financial institutions for low volume, high value transactions.


Creditor Identifier - In order to collect a SEPA Direct Debit, each creditor must obtain a Creditor Identifier form their bank which uniquely identifies the creditor throughout the SEPA payment region.


Method of exchanging funds between financial institutions.

Core Reference

The unique reference applied to a Direct Debit Instruction (DDI). The reference must be a minimum of six alpha numeric, upper case characters which matches the DDI to the subsequent Direct Debit payment.

Counter Claim

A claim raised by a service user against a paying bank following settlement of a disputed indemnity claim.

back to top



Database Management System.


Direct Debit Advance Notice - when a direct debit is set up or changed, the originator must give the payer an advance notice of the change. Bacs stipulate the amount of notice required. Advance notice letters may be sent by email or post.


Direct Debit Instruction - An authority signed by the customer allowing the originator to collect Direct Debit payments from his/her account.


Direct Debit Indemnity Claim Automation.

Destination Account

The account where the transmitted funds are received.

Direct Credit

A Bacs Direct Credit is an electronic payment made through Bacs directly into the recipient's bank or building society account.

Direct Debit

A payment of an agreed amount collected from a customer’s bank account by a service user. The amounts and dates may vary for each payment.

Direct Debit Guarantee

The guarantee offered by the paying banks to payers in respect of the Direct Debit Scheme advising payers of their rights and safeguards.

Direct Debit Software

Managing Direct Debits involves many responsibilities associated with the Direct Debit Scheme. Direct Debit Management Software handles many of the complexities of direct debits, such as the Direct Debit Advance Notice (DDAN) letters and Bacs transaction codes. Mosaic Software is the leading supplier of Direct Debit Software.

Direct Submitter

A Direct Submitter makes a connection to Bacs directly (as opposed to using a bureau). To become a direct submitter, a user must obtain authority from their sponsoring bank and use Bacs Approved Software to make use of the Bacstel-IP service.

Dormancy Period

A period, normally 13 months, from the date of the lodgement of the Direct Debit Instruction, or last Direct Debit payment, after which a paying bank will delete details of a DDI because no payments have been collected.

Due Date

The date the Direct Debit is due as advised to the payer in the Direct Debit Advance Notice.

back to top


Entry Day

Day 3 of the Bacs cycle (see Bacs cycle).


Electronic Funds Transfer - the movement of funds by electronic means from one account to another.


European Payments Council


When a Direct Debit Instruction has expired.

back to top



A self balancing set of records.

back to top


back to top



A scripting language.


A networking protocol.

back to top



International Bank Account Number


A document which contains a legally binding obligation to make payment to a paying bank in the event of an indemnity claim. An indemnity, in standard form, is an essential requirement of the Direct Debit Scheme.

Indemnity Claim

A claim made by the paying bank in respect of an incorrect Direct Debit being applied to an account.

Industry Sector

An area of business e.g. Publishing.

Input Day

Day 1 of the Bacs cycle (see Bacs cycle).

Input Deadline

The time by which a transmission must be completed if the items are to be processed on the following processing day.

Input Report

A report sent to the originator to confirm the processing of a file (available to the originator on input day).

Interbank Transfer of Direct Debit Instructions

A service to assist customers when moving their accounts to a different bank or building society. The service electronically transfers Direct Debit and Standing Order information between the banks or building societies. Also known as Transfer of Direct Debit and Standing Orders (ToDDaSO).

Internet Protocol

Computer technologies that enable many computers to exchange information reliably and efficiently.

Irregular Payments

Payments which occur more than once in a 13 month period.


Industry Sorting Code Directory - consolidates all Cheque and Credit Clearing, CHAPS and Bacs sort code related information, including data held in the Reeds Sorting Code Directory.


Integrated Services Digital Network - technology used to transmit high speed digital data through a single channel over telephone lines.


The ISO 20022 is an XML message standard used to initiate SEPA Direct Debits. Some banks may accept other formats from businesses to initiate the SEPA direct debits and the bank itself will perform the conversion. However, some banks are now expecting their customers who want to initiate SEPA direct debits to provide the data in ISO20022 format.


A single Bacs transaction.

Item Limit

An upper monetary amount set against individual items at the request of a service user. It is noted on the input report if this limit is exceeded.

back to top


Julian Date

This is the number given to a day-of-year. The numbers run sequentially through the year 1 January is always 001 31 December is 365 (366 if a leap year).

back to top


back to top


Limit Value

A financial limit agreed with the sponsoring bank for a fixed period of time on an individual account.

Live Status

An organisation or bureau, which has successfully submitted test files and has been authorised to submit live files to Bacs.

Lodgement (lodged)

The process by which paying bank accepts the Direct Debit Instruction (DDI).

back to top



Mosaic's software for the complete management of Direct Debits.


A bank or building society that is a member of Bacs.

Migration (AUDDIS)

When an originator transfers non AUDDIS Direct Debit Instructions to the automated AUDDIS system (see AUDDIS).

Modulus Checking

An arithmetic computation performed on an account number based on the rules produced by each bank. It is used to validate the sort code and account number combination in products like BankCheck, BacscomIP and Mandate.

back to top


Nominated Account

The originating account from which credit/debit transactions are to be distributed.

Notice of Expiry

Notice of an expiring direct debit instruction to Bacs, by the use of the transaction code 19 by the originator, which signifies the final payment.

back to top


On or Immediately After

On or within three bank working days of the specified payment date given in the advance notice.

Originating Account

The account from which a payment originates.

Over Limit

Referral of a file which exceeds the limit set up by the sponsor for the nominated account.

back to top



Postal Address File maintained and distributed by the Royal Mail. It contains the details of all 30+ million addresses in the UK. The PAF database is used by our postcode lookup software PostcodeIT.

Paperless Direct Debit

Paperless Direct Debit allows an organisation to accept direct debit instructions over the telephone or on the internet. The payer does not need to sign a direct debit mandate. This speeds up the process of accepting instructions.

Participants of the Direct Debit Scheme

Sponsors, Service users and the Paying banks.


The person, who by signing a Direct Debit Instruction (DDI), has given authority for their account to be debited by the service user using the direct debit scheme.

Payer's Branch

The Bank or Building Society branch holding the payers account.

Paying Bank

The bank maintaining the payers account.

Payment Date

The date a Direct Debit is due to be debited from the payers account.


Public Key Infrastructure - A computer technology to ensure the exchange of information between individuals and computer systems is secure. It allows a trusted organisation to issue digital certificates to people and organisations and is generally used in conjunction with Internet protocol (IP). The certificates are used to prove identity and can be used to digitally sign documents and transactions. The signature proves the authenticity of the transaction and also proves that the data exchanged has not been modified or tampered with. Digital signatures are now acceptable in a court of law. The same technology is also used to encrypt data in transit so nobody other than the intended recipient can read it.

Processing Cycle

The minimum time taken for a payment instruction to be submitted to Bacs for processing and the funds to reach the destination account (see Bacs cycle).

Processing Day

Day 2 of the Bacs cycle (see Bacs cycle).

back to top


back to top


Receiving Account

The account the transmitted funds are received. Also referred to as the Destination account.


For Bacs, a record that relates to a credit or debit transaction.


The reference allocated by a service user to each Direct Debit Instruction (DDI) and Direct Debit. (see Core Reference).

Refund Request

A claim which is not covered by the valid claim criteria, generally when a bank has made a payment in error.


A Direct Debit that has been returned unpaid to the originator and is being resubmitted for payment.

back to top



SEPA Direct Debit


(Single Euro Payment Area) Single European Payment Area. Allows businesses to move currency throughout the EU as easily as domestic payments. Transactions in SEPA are handled using ISO20022 message format.

Service User

A company, group of companies, charity etc. that is sponsored by their bank to use one or more Bacs service.

Service User Guide Bacstel-IP

The technical specification for submission to Bacs.

Service User Number

A unique six digit number allocated to an organisation authorised to use the Bacs service.(Formerly OIN - Originator's Identification Number)


Secure Hash Algorithm 2. A hash is a mathamatical operation which is performed on your digital data, in the context of Bacs the data is some data Bacs present you with when loging into Bacs or it is your payment file. When a user digitally signs a payment file using SHA-2, Bacs will check the hash on receipt and be able to confirm the file has not been altered between signing and receipt.

Single Payment

A Direct Debit which will only be collected once.


Simple Object Access Protocol - a protocol specification for exchanging information in the implementation of Web services.

Solution Supplier

A Bacs solution supplier is a company approved by Bacs to supply software solutions to businesses wishing to access the Bacs service. (See BASS).

Sort Code Directory

This is the directory of valid sort codes maintained by the paying banks. Service users use this directory to check a payer’s sort code is correct.

Standing Order

A Standing Order is an instruction to a bank to pay a regular amount to a recipient's bank or building society account. Only the bank account holder can amend the instruction.

Sorting Code

A six digit code uniquely identifying the bank and branch location where an account is held.

Sponsor/Sponsoring Bank

A bank or building society, which is a Bacs member ,authorising organisations and bureaux to submit data to Bacs for processing.

Standing Order

An instruction given by a customer to their bank to make a payment of a fixed amount on specified regular dates to a named individual or organisation.


Service User Number

back to top


Three Day Cycle

The service offered by Bacs where the minimum time taken for the processing cycle is three processing days. (See Bacs Cycle)


Transport Layer Security - TLS is a protocol used to ensure the privacy of data while it is being transported over the internet. From 13th June 2016, Bacs will only support TLS 1.1 and 1.2.

Trading Name

The name a company uses for trading purposes. This name may differ from the registered name.

Transaction Code

A series of codes used in connection with transactions processed through Bacs to determine the type of transaction, for example, for Direct Debits - 01, 17, 18, 19 - AUDDIS Instruction 0S, 0C, 0N. Direct credits use the transaction code 99.

back to top


Unpaid Direct Debit

A Direct Debit that is returned uncollected by the paying bank.

Unpaid Direct Debit Reason Codes

The codes used to identify the reason for returning an unpaid Direct Debit either by automated means via Bacs (ARUDD) or by manual advice.

back to top



VocaLink (formerly Banks Automated Clearing System) is the commercial company that processes Direct Debit and Bacs Direct Credit payments, and maintains the payment network.

back to top


Working Days

For the purposes of the Direct Debit Scheme, working days are defined as English bank working days excluding Saturdays, Sundays and Bank Holidays.

back to top


back to top


back to top


Mosaic Software logo
Support is available 9am-5pm, Monday to Friday excluding bank holidays. We also have out of hours support available in case of emergency.
Contact Us