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Guidance

TAG data book

Historical and reference information on all the appraisal and modelling values referred to in the transport analysis guidance (TAG).

From:
Department for Transport
Published:
29 November 2018
Last updated:
5 November 2026 — See all updates

Documents

TAG data book

5.75 MB

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Forthcoming change: a new series for the price of charging an electric vehicle

https://www.gov.uk/government/publications/forthcoming-changes-and-previous-versions-of-tag/forthcoming-change-a-new-series-for-the-price-of-charging-an-electric-vehicle

Forthcoming change: discount rate changes in TAG

https://www.gov.uk/government/publications/forthcoming-changes-and-previous-versions-of-tag/forthcoming-change-discount-rate-changes-in-tag

Forthcoming change: electric Vehicle Excise Duty in the TAG data book

https://www.gov.uk/government/publications/forthcoming-changes-and-previous-versions-of-tag/forthcoming-change-electric-vehicle-excise-duty-in-the-tag-data-book

Forthcoming change: new method to uprate the freight value of travel time

https://www.gov.uk/government/publications/forthcoming-changes-and-previous-versions-of-tag/forthcoming-change-new-method-to-uprate-the-freight-value-of-travel-time

Forthcoming change: updates to TAG economic and demographic parameters

https://www.gov.uk/government/publications/forthcoming-changes-and-previous-versions-of-tag/forthcoming-change-updates-to-tag-economic-and-demographic-parameters

Details

The TAG data book provides all of the appraisal and modelling values referred to in TAG guidance. The data book features historical information and factual reference information about the appraisal and modelling values.

The previous version, TAG data book v2.02, was released in December 2025.

TAG provides information on the role of transport modelling and appraisal, and how the transport appraisal process supports the development of investment decisions to support a business case.

Updates to this page

Last updated:
5 November 2026
Show all updates

  1. Added forthcoming changes, which are expected to be released in December 2026.

  2. TAG data book updated.

  3. Added forthcoming changes on appraisal, electric vehicle mileage share, Green Book, occupancy and journey purpose split updates.

  4. Added 'Forthcoming change: updates to road freight values of travel time'.

  5. Tag data book updated.

  6. Added forthcoming change: appraisal data update.

  7. TAG data book updated.

  8. Added 'Forthcoming change: appraisal data update'.

  9. TAG data book updated and forthcoming changes for May 2025 added.

  10. Added 'Forthcoming change: updates to economic and demographic data and clarified guidance on rail appraisal'.

  11. Unit updated and May 2024 forthcoming change note removed.

  12. Forthcoming changes added.

  13. TAG data book updated.

  14. Added forthcoming change about appraisal guidance updates.

  15. Added forthcoming change about carbon valuation.

  16. TAG data book updated.

  17. Added forthcoming change: spring 2023 data book and guidance updates.

  18. TAG data book updated.

  19. TAG data book updated.

  20. Forthcoming changes for November 2022.

  21. Tables A1.3.11 and A1.3.12 in 'TAG data book: fleet assumptions' have been corrected to reflect the addition of electric PSV energy consumption parameters.

  22. Updated TAG data book. Added data book: fleet assumptions, and a forthcoming change note on fleet assumptions.

  23. Forthcoming change to guidance note added, the note details guidance alterations to be implemented in May 2022.

  24. Updated TAG data book.

  25. Notification of forthcoming change for November 2021.

  26. Added forthcoming change data book with updated carbon values and marginal external costs.

  27. Added latest version of TAG data book and removed sensitivity testing document.

  28. Added forthcoming change to TAG data book.

  29. Added new data book: TAG data book - sensitivity training.

  30. Annual Parameters source note corrected to refer to source material referenced in November 2019 forthcoming change, and outturn data based on ONS March 2020 publications. Marginal External Costs corrected for weighted average of congestion bands (A5.4.1), band 5 London motorways (A5.4.2), and Scotland values (A5.4.4). Environmental analysis tables corrected for fuel/electricity price forecasts and fleet splits by fuel type. Average value of accident prevention per casualty (A4.1.1).

  31. Update to outturn and forecast data for GDP, inflation and average earnings, based on estimates from the ONS and projections from the OBR (due to be published alongside Autumn budget); update to the forecast values for Marginal External Costs based on estimation by the Department’s National Transport Model. Tables A5.4.1 - A5.4.4 will be updated as a result; update to the professional drivers’ values of time to reflect latest Annual Survey of Household Earnings data.

  32. October 2019 forthcoming changes document added.

  33. Corrected light goods vehicles formulas in table A1.3.10a.

  34. TAG Data Book re-published with slight correction affecting the look-up year in sheet A1.3.7.

  35. Updated reflecting the forthcoming changes given new forecasts from the ONS and OBR.

  36. 2019 forthcoming changes document added.

  37. First published.

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