Official Statistics

Annual savings statistics: background quality report

Updated 19 September 2024

1. Contact

• Organisation unit - Knowledge, Analysis and Intelligence (KAI)
• Names - K Ismail, A Jenkins, L Carrick, A How
• Email – [email protected]

2. Statistical presentation

2.1 Data description

This quality report relates to the Annual Savings Statistics, an official statistics publication, and its purpose is to provide users with information about the quality of the outputs as set out by the Code of Practice for Statistics.

The publication is released annually and provides information on the following tax-free savings products: Individual Savings Accounts (ISAs), Junior ISAs (JISAs), Lifetime Individual Savings Accounts (LISAs), Child Trust Funds (CTFs), and Help to Save (HtS).

Please see section 2.4 for further details on the terminology used in the publication. More information on the policy background and descriptions of the tables contained in the publication can be found in the background and methodology note.

2.2 Classification system

Breakdowns of data are based on the information available in the returns and application programming interface (API) information used to compile the statistics.

Individual level data is aggregated by National Insurance number or unique account identifier as appropriate, while provider level information is grouped by financial institution code.

2.3 Sector coverage

These statistics cover all ISA, JISA, LISA, CTF and HtS accounts held in the UK.

2.4 Statistical concepts and definitions

Financial year

A financial year runs from 1 April until 31 March the following year. HtS statistics are analysed using financial years.

Tax year

A tax year runs from 6 April to 5 April the following year. ISA, JISA, LISA, and CTF statistics are analysed using tax years.

Subscriptions

Savings that are newly invested in an ISA, JISA, LISA or CTF during a tax year, or HtS account during a financial year.

Holdings

Value of savings accumulated in an account (including capital growth, interest, and dividend or other income retained in the account). Holdings are also known as investments.

ISAs

Tax-free savings accounts with an annual subscription limit of £20,000. There are four types of ISA: cash, stocks and shares, innovative finance and Lifetime. More information on ISAs can be found at GOV.UK.

Junior ISAs

Long-term tax-free savings accounts for children that became available in November 2011. More information on JISAs can be found at GOV.UK.

Child Trust Funds

Long-term tax-free savings accounts opened for all children born between 1 September 2002 and 2 January 2011. More information on CTFs can be found at GOV.UK.

Lifetime ISAs

Long-term tax-free savings accounts with an annual subscription limit of £4,000. A 25% bonus is added by the government on any subscriptions. LISA funds can only be withdrawn tax free under certain circumstances. More information on LISAs can be found at GOV.UK.

Help to Save

A savings account that allows eligible working people to save up to £50 each month. A 50% bonus is received at the end of the second and fourth years based on the highest balance achieved over the previous two years. More information on HtS can be found at GOV.UK.

2.5 Statistical unit

The units used in the statistics are:

• number of individuals holding or interacting with accounts
• number of accounts
• value of transactions or holdings
• quantity of transactions

2.6 Statistical population

All holders of ISA, JISA, LISA, CTF and HtS accounts in the UK.

2.7 Reference area

This analysis is presented for a single region – the UK. Regional breakdowns are given for the different regions of the UK.

2.8 Time coverage

CTF and ISA tables 9.7 to 9.12 cover the latest tax year for which a complete set of statistical returns is available.

ISA tables 9.4 and 9.6 contain statistics from the latest tax year for which a complete set of statistical returns is available, back to 2008 to 2009 and 2011 to 2012 respectively.

LISA statistics cover the latest tax year for which a complete set of statistical returns is available, back to 2018 to 2019.

HTS statistics cover the latest financial year for which a complete set of statistical returns is available, back to the beginning of the trial period (January 2018).

3. Statistical processing

3.1 Source data

Individual Savings Accounts (ISAs)

ISA25 form - Provides the total amount subscribed to ISAs during the tax year and number of ISA accounts that received a subscription.

ISA14 form - Provides the total market value of all ISA accounts at the end of the tax year, as well as an investment category split for the value of stocks & shares ISAs.

ISA14A form - From February 2020, this form combines and supersedes the ISA14 and ISA25 forms.

ISACOMM100 (magnetic media returns) - Provides information on ISA accounts, specifying the type of ISA, total market value, and amount subscribed during the year.

Survey of Personal Incomes (SPI) - Survey based on information held by HMRC on individuals who could be liable to UK Income Tax. It is carried out annually by HMRC and covers income assessable to tax for each tax year. More information on the SPI can be found in the statistics about personal incomes collection on GOV.UK.

Lifetime Individual Savings Accounts

LISA API - An online system used to create or make changes to LISA accounts and manage transactions.

Child Trust Funds

CTF electronic returns - Providers report details for all CTFs they managed during the return period, including CTFs transferred in and CTFs where the account holder has died.

Junior ISAs

JISA 14a Stats – Provides subscriptions to and market values of JISAs.

Help to Save

NS&I returns - Weekly datasets submitted to HMRC on HtS accounts, payments, and withdrawals.

3.2 Frequency of data collection

LISA data is collected monthly via the API system.

Help to Save data is received by HMRC weekly.

Data for ISAs and CTFs is received annually.

3.3 Data collection

LISA data is collected as a function of the LISA API.

HMRC receive HtS data from NS&I.

The deadline for ISA, JISA and CTF managers to submit their returns for the previous tax year is 4 June, 60 days after the end of the tax year. Working with compliance colleagues within HMRC, we identify and follow up with providers who have failed to submit returns. CTF managers who submit late returns are sent a reminder and may be charged penalties for making an incorrect return.

3.4 Data validation

Checks carried out on the data include:

• ISA records are validated by checking variables are in the correct format. If errors are found, these records are written to a discard file and an error message is recorded. Remaining records are then loaded into an analytical environment.

• LISA and CTF data arrive as extract text files and are processed in batch. Validation checks are run on the data types and the lengths of the incoming fields to ensure they conform to what is expected, and to ensure that there are no embedded delimiters in the fields.

• HtS data received from NS&I is quality assured before being uploaded through a secure file transfer system.

• Secondary data validation checks take place during the analytical process, removing records, or flagging for further investigation.

3.5 Data compilation

Imputation and grossing for missing data

Where a provider has not submitted a return, and has not ceased acting as a provider, values are imputed using the figures reported in their submission from the previous tax year.

Aggregating data

Individual level data is aggregated by National Insurance number or unique account identifier, while provider level information is grouped by financial institution code. These unique identifiers do not change over time.

4. Quality Management

4.1 Quality assurance

All official statistics produced by KAI must meet the standards in the Code of Practice for Statistics produced by the UK Statistics Authority and all analysts adhere to best practice as set out in the ‘Quality’ pillar.

Analytical Quality Assurance (QA) describes the arrangements and procedures put in place to ensure analytical outputs are error free and fit-for-purpose. It is an essential part of KAI’s way of working, as the complexity of our work and the speed at which we are asked to provide advice means there is a high risk of error which can have serious consequences on KAI’s and HMRC’s reputation, decisions, and in turn, on people’s lives.

Every piece of analysis is unique, therefore there is no single QA process that contains all the QA tasks needed for every project. However, analysts in KAI carry out QA checks on data inputs and outputs, and generally adapt QA tasks to make them appropriate to each piece of analytical work. Teams amend and adapt as they see fit, considering the level of risk associated with their analysis and the different QA tasks that are relevant to the work.

Analysts and managers construct a plan for all QA tasks, creating a checklist specific to the project. Analysts carry out the tasks during and at the end of the analysis.

Work is quality assured at various times through its iterations and then passed to the Senior Responsible Officer for final review and sign-off.

4.2 Quality assessment

The QA for this project adhered to the framework described in section 4.1. The specific procedures undertaken were:

Stage 1 – Specifying the question

Up to date documentation was agreed with stakeholders setting out outputs needed and timescales, how the outputs would be used, and all the parameters required for the analysis.

Stage 2 – Developing the methodology

Methodology was agreed and developed in collaboration with other teams, ensuring it was fit for purpose and would deliver the required outputs.

Stage 3 – Building and populating a model/piece of code

The analysis was produced using the most appropriate software and in line with good practice guidance.

Data inputs were checked to be fit for purpose by reviewing available documentation and through consultation with data owners or suppliers.

QA of the input data was carried out. Any inconsistencies or data issues were raised with data holders.

The analysis was audited by someone other than the lead analyst; both the code and methodology were checked.

Stage 4 – Running and testing the model/code

Results were compared with those produced in previous years and differences understood and determined to be genuine.

Results and trends were determined to be explainable and in line with expectations.

Stage 5 – Drafting the final output

Checks were completed to ensure internal consistency.

Final outputs were independently proofread and signed off by a senior statistician.

5. Relevance

5.1 User needs

This analysis is likely to be of interest to users under the following broad headings:

• national government – policy makers and MPs
• regional and local governments
• academia and research bodies
• media
• business community
• general public

5.2 User satisfaction

Formal investigations into user satisfaction have not been undertaken, however KAI are always open to ideas for new analysis to meet changing user requirements.

There is contact information for customers to give feedback and comments on GOV.UK.

The Savings Team regularly communicate with HMRC and HM Treasury colleagues to ensure that these statistics meet their information requirements.

5.3 Completeness

It is a legal requirement for information on ISAs, JISAs, LISAs, CTFs and Help to Save to be submitted via returns from third parties, or via the LISA API. The statistics contained in this report can be considered as complete.

6. Accuracy and reliability

6.1 Overall accuracy

This analysis is based on administrative data, and accuracy is addressed by eliminating non-sampling errors as much as possible through adherence to the QA framework. Where necessary, information is queried with providers.

Potential sources of error include:

• providers or managers entering or submitting incorrect information into their returns
• human or software error when entering and submitting return data or entering information into the API
• human or software error when HMRC compiles aggregate datasets
• mistakes in the code used to analyse the data and produce the statistics, or by analysts interpreting the data incorrectly

6.2 Sampling error

Sampling error is only a possibility for the ISA statistics where data from the SPI is used. Information on the measures of precision can be found in the SPI supporting documentation.

6.3 Non-sampling error

Coverage error

Not applicable.

Measurement error

The main sources of measurement error in these statistics can be categorised as respondent errors and include the following:

• third parties making errors entering their information on returns
• data entered incorrectly into databases, either manually or by electronic transmission

There is a risk that errors from providers with a high number of accounts could distort the overall statistics. To mitigate this, checks are conducted on the input datatables before the statistics are produced, and any unexpected large values are investigated and corrected if required.

Non-response error

The deadline for ISA, JISA and CTF managers to submit their returns for the previous tax year is 4 June. Working with compliance colleagues within HMRC, providers that have failed to submit returns are identified and followed up. CTF managers who submit late returns are sent a reminder and may be charged penalties for making an incorrect return.

Known missing returns are imputed to reduce non-response error.

Processing error

It is possible that errors exist in the code used to analyse and produce the statistics. This risk is reduced through developing a good understanding of the objectives, the code, the analysis, and the outputs, as well as through thoroughly quality assuring each phase of the statistical process.

6.4 Data revision

Data revision – policy

The UK Statistics Authority Code of Practice for Statistics requires all producers of official statistics to publish transparent guidance on the policy for revisions.

Data revision – practice

All figures in this publication are subject to revision where inconsistencies are identified.

Information in Tables 9.4 and 9.6 of the ISA statistics are from annual returns (ISA14A). If returns are submitted late, tables will be revised the following year.

6.5 Seasonal adjustment

Not applicable.

7. Timeliness and punctuality

7.1 Timeliness

These statistics are published annually to a pre-announced date in line with the national Code of Practice for Statistics. This allows sufficient time for capturing and uploading submissions with any related delays, for data validation and quality assurance steps, and finally for the compilation of the statistics themselves.

From 2024, the publication month has been changed from June to September to allow the publication of two additional years of Child Trust Fund data.

These statistics use the most recent, available year of data from each source.

7.2 Punctuality

In accordance with the Code of Practice for Statistics, the exact date of publication will be given more than one calendar month before publication on the schedule of updates for HMRC’s statistics. Any delays to the date will also be announced there.

The full publication calendar can be found on both the schedule of updates for HMRC’s statistics and the research and statistics calendar on GOV.UK.

8. Coherence and comparability

8.1 Geographical comparability

This analysis is presented for a single region – the United Kingdom. Regional breakdowns are given for the different regions of the UK, comparable with other publications.

8.2 Comparability over time

When comparing tables between years, changes to rules and limits for each savings product or changes to statistical methodology should be taken into account. Changes will be described in the relevant data tables.

From the 2017 to 2018 tax year, the match rate between SPI and ISA records was improved. As a result, it is not recommended to compare between ISA tables 9.7 to 9.12 from years before and after this date.

8.3 Coherence – cross domain

ISA savings are included in the Office for National Statistics Wealth and Assets Survey but cannot match the level of coverage and timeliness that this direct method of collection offers.

Historical data going back to the introduction of ISAs in 1999 to 2000 can be viewed in the National Archives. However, ISA tables statistics only cover one aspect of the savings options of individuals and are subject to annual savings limits which have fluctuated over time, so do not necessarily provide an insight into personal sector savings in a wider UK National Accounts context.

Coherence – sub-annual and annual statistics

All statistics are presented as annual outputs. No coherence issues exist.

Coherence – national accounts

Not applicable for this publication.

8.4 Coherence – internal

Rounding of numbers may cause some minor internal coherence issues as the figures within a table may not sum to the total displayed. Effort has been made to ensure totals between tables remain constant where appropriate.

9. Accessibility and clarity

9.1 News release

Figures from this publication have been referenced by a number of industry articles since release.

9.2 Publication

The tables and associated commentary that comprise the Annual Savings Statistics are published on the Annual Savings Statistics webpage on GOV.UK. Tables are published in the OpenDocument format, and the associated commentary as an accessible HMTL.

Both document types comply with the accessibility regulations set out in the Public Sector Bodies (Websites and Mobile Applications) (No. 2) Accessibility Regulations 2018. Further information can be found in HMRC’s accessible documents policy.

9.3 Online databases

This analysis is not used in any online databases.

9.4 Micro-data access

Access to this data is not possible in micro-data form due to HMRC’s responsibilities around maintaining taxpayer confidentiality.

9.5 Other

There are not any other dissemination formats available for this analysis.

9.6 Documentation on methodology

Background and guidance on interpreting Annual Savings Statistics is publicly available to users from the Annual Savings Statistics webpage.

9.7 Quality documentation

All official statistics produced by KAI must meet the standards in the Code of Practice for Statistics produced by the UK Statistics Authority and all analysts adhere to best practice as set out in the ‘Quality’ pillar.

Information about quality procedures for this analysis can be found in section 4 of this document.

10. Cost and burden

Because all necessary data for the savings statistics is obtained from administrative sources or previously published statistics, there is no additional burden on companies to provide information.

It is estimated to take about 30 days full time equivalent work to produce the annual publication.

11. Confidentiality

11.1 Confidentiality – policy

HMRC has a legal duty to maintain the confidentiality of taxpayer information.

Section 18(1) of the Commissioners for Revenue and Customs Act 2005 sets out our duty of confidentiality.

This analysis complies with this requirement.

11.2 Confidentiality – data treatment

All data is handled internally in line with the HMRC statistics policy on confidentiality and access to third party information.

There is no disclosure risk in the published ISA statistics given the very large number of individuals holding ISAs. However, there is a risk among Junior ISA providers and statistical suppression has been necessary to preserve confidentiality.

Further information on anonymisation and data confidentiality best practice can be found on the Government Statistical Service’s website.