Part 4: Dual List Maintenance
The Valuation Office's technical manual for the rating of business (non-domestic) property.
This relates to the treatment of an assessment in either the 2023 or 2026 Rating Lists following completion of cases (check, challenge, appeal or maintenance) in the alternative (earlier or later) list.
It does not cover action to be taken in respect of ‘consequential’ alterations to similar hereditaments (either by virtue of location or class) as a result of changes to the 2023 or to the 2026 list entries for the subject property.
1: There are two types of Dual List Maintenance (DLM), forward and backward.
‘Forward’ relates to alterations made in the 2023 lists that potentially need to be reflected in the 2026 lists.
‘Backward’ relates to alterations made in the 2026 lists that potentially need to be reflected in the 2023 lists.
2: Initially cases of forward DLM will be more prevalent as we settle 2023 casework. However, as we move into the life of the 2026 rating lists backward DLM will be more usual.
3: From 1 April 2027 backward DLM will cease as the 2023 lists can only be altered as a result of a proposal or appeal. However, transitional relief certificates (in England) will continue to be needed — see RM Section 3 Part 5 for details of which certificates are required.
4: DLM will be considered necessary unless:
- the change relates to the tone on one list only
- the change is a temporary allowance that ceased prior to 1 April 2026
- there are further 2026 changes to follow
- the change is an Material Change of Circumstance (MCC) that applies in one list only
- the 2023 assessment would increase but we are precluded from backdating the increase (but have regard to the potential need to issue transitional relief certificates)
5: The introduction of Check, Challenge, Appeal (CCA) changed how challenges are made to rating assessments from 1 April 2017 (in England) and 1 April 2023 (in Wales) and therefore forwards DLM is not always appropriate.
6: High level Principles that apply — but see paragraph 8 and scenarios.
6.1 2023 list casework with 2026 potential DLM
As a general rule, where the change is a physical change to the property and factual — DLM will usually apply.
As a general rule, where the 2023 list entry is the result of an agreement at tribunal decision DLM should not be carried out — the previous agreement or decision should stand. In that circumstance, DLM is only required if the 2023 list change relates to an MCC that occurred after the Material Day of the previous alteration.
As a general rule. where the change relates to value, treatment of disabilities, line adjustments or end allowances DLM will apply only in exceptional circumstances — it will depend on the assumptions made in the valuation basis for the particular list.
6.2 2026 list casework with 2023 potential DLM
Where the change is physical and factual and subject to date of change before 1 April 2026 — DLM will apply.
Where the change relates to value, treatment of disabilities, line adjustments or end allowances if there is no relevant 2023 list case outstanding the caseworker should consider whether there is clear evidence to demonstrate that the rating assessment in the 2023 list is inaccurate and if so correct it. Where it is not possible to amend the 2023 list issue transitional relief certificates (England only) as appropriate.
In all cases of DLM this should be done as quickly as possible to ensure that billing authorities are able to process changes correctly.
7: Matters to consider before undertaking DLM
The following matters need to be considered before making the judgement whether to undertake DLM:
- when was the material day of the completed alteration to the relevant list
- what was the reason for the change in the relevant list — normal ongoing maintenance (Business Authority Report or Valuation Office Report), settlement of appeal, Valuation Tribunal decision
- has an inspection been carried out — if so, when, was it full, partial, or just external
- to what extent were facts checked
- was the change because of factual changes or valuation changes or a combination of both
8: The table in appendix 1 shows the scenarios likely to be encountered and the action to be taken.
9: 2029 Revaluation — Triple List Maintenance
In addition to forward (2023 to 2026) and backward (2026 to 2023) DLM, any change to the 2026 assessment will also trigger a change to the 2029 Reval case survey. This is generally referred to as Triple List Maintenance (TLM) or Data Ripple.
In most instances these changes will be automatic. The survey will be copied automatically from the 2026 list to the 2029 list case. It will only be in rare circumstances — where the 2029 Reval case has had data changes made and is protected — where changes to the Reval case survey will be required.
1: Forward DLM (2026 list following 2023 alteration)
| Event | Scenario | DLM or CCA? | Questions/Comments/Recommendation |
|---|---|---|---|
| Reconstitution | Hereditament split, merged, or reconstituted in 2023 list, and revised entries still shown for 31 March 2026 | DLM | Recons should be replicated for 2026 |
| Address changes — 1 to 1 recons (Codes 02/11 or 06/14) | Address-only change — no change in unit of assessment or other facts | DLM | Address-change Recons should be replicated for 2026 |
| Partial demolition | 2023 rateable value reduced (either by notice or agreement). | DLM | Consider facts on 1 April 2026 but presumption is that the 2026 is amended to reflect changed facts |
| Extension built | Rateable value increased (by Billing Authority Report, Valuation Office Report or interested party proposal (IPP)) in 2023 list | DLM | Consider facts on 1 April 2026 but presumption is that the 2026 is amended to reflect changed facts |
| Valuation issues | Scenario 1 — 2023 tone reduced on appeal — either zone A or rate/m2 | CCA | Almost always list specific so DLM not appropriate |
| Valuation issues | Scenario 2 — 2023 (end) allowance conceded | CCA | Almost always list specific so DLM not appropriate |
| Mixed or factual and valuation issues? | Scenario 3 — 2023 tone reduced and part demolition | DLM | Reflect change of facts only |
| Deletions | Scenario 4 — Property deleted by notice or by agreement | DLM | Delete for 2026 |
| Completion notices | Scenario 5 — Date specified before 1 April 2026 | DLM | Insert in 2026 list by DLM |
| External MCC | Scenario 6 — road works commencing before 1 April 2026 | CCA | No DLM — signpost to CCA as compiled list error |
| External MCC | Scenario 7 — opening up of competitor business (for example Wetherspoons) before 1April 2026 | CCA | No DLM — signpost to CCA as compiled list error |
| Exemptions (including partial exemption) | Scenario 8 — farm office, exemption conceded on IPP with effect from 1 May 2025 and facts recently obtained | DLM | DLM only if Valuation Office is satisfied that on 1 April 2026 the facts are the same. If facts at 1 April 2026 unclear then direct via CCA |
| Exemptions (including partial exemption) | Scenario 9 — special school. Deleted from list with effect from 1 June 2025 by Billing Authority Report and facts recently obtained. | DLM | DLM only if Valuation Office is satisfied that on 1 April 2026 the facts are the same. If facts at 1 April 2026 unclear then direct via CCA |
| Composites — a property becoming a composite or an increase in amount of non-domestic | Scenario 10 — house becoming partly non-domestic property (for example flat above shop converted to storage). 2023 list altered by Billing Authority report, Valuation Office report or agreement of IPP and reasonable to assume same applied at 1 April 2026 | DLM | DLM (also add composite indicator) and ensure Council Tax entry is aligned |
| Composites — a reduction in amount of non-domestic | Scenario 11 — storage above shop converted to include in owner’s flat — 2023 list altered by Billing Authority report, Valuation Office report or agreement of IPP and facts unclear | CCA | Liaise with Council Tax — if recently inspected for Council Tax and all relevant facts for Non-Domestic Rating confirmed then DLM |
| Evidence provided shows that the 2026 list is inaccurate (too low) | Scenario 12 — this is more likely to occur in receipt-based valuations where the 2026 has been estimated and actual receipts have been provided during or prior to 2023 list negotiations | DLM | DLM to correct |
2: Backward DLM (2023 list following 2026 alteration)
There is a difference between what needs to be done up to 31 March 2027 and thereafter. Up to 31 March 2027 the Valuation Office can still usually alter the 2017 list therefore transitional relief certification is not normally appropriate. After this date the 2023 list is effectively closed, and it will be necessary to consider whether a transitional relief certificate should be issued. In Wales the transitional relief scheme is applied by the Billing Authority so there is no requirement for transitional relief certification. All references to transitional relief certificate are applicable to England only.
Where there is a 2023 list IPP outstanding then DLM should still be carried out where appropriate.
Where the 2023 list entry is as a result of an agreement or a valuation tribunal decision then DLM should not be carried out to further amend.
| Event | Scenario | Before 1 April 2027 | After 1 April 2027 | Questions, comments and recommendation |
|---|---|---|---|---|
| Reconstitution | Hereditament split, merged or reconstituted with effect from 1 April 2026 by Billing Authority report or CCA | DLM | Transitional relief certificate | Necessary for transitional relief purposes to align lists entries so DLM. If circumstances arose on 1 April 2026 then schedule transitional relief certificate required. After 31 March 2027, if circumstances arose before 01 April 2026 then Reg 19 transitional relief certificate required |
| Address-only change — 1 to 1 recons (Codes 02/11 or 06/14) | Not applicable | Not applicable | Not applicable | Unlikely to be necessary to alter 2023 list |
| Partial demolition | Scenario 1 — 2026 rateable value reduced (either by notice or agreement) | DLM | Transitional relief certificate | Consider confidence in facts and effective date of event subsisting prior to 01 April 2026 |
| Extension built before 1 April 2026 | Scenario 2 — rateable value increased (by Billing Authority report, Valuation Office report or IPP) in 2026 list with effective from date of schedule | DLM if date of extension known otherwise transitional relief certificate | transitional relief certificate | Consider confidence in facts and effective date of event subsisting prior to 01 April 2026 |
| Valuation issues | Scenario 3 — 2026 tone reduced — either zone A or rate/m2 | Not applicable | Not applicable | Almost always list specific so DLM not appropriate. If 2023 list tone affected, then DLM or transitional relief certificate may be required — consult Rating Technical Lead |
| Valuation issues | Scenario 4 — 2023 (end) allowance conceded | Not applicable | Not applicable | Almost always list specific so DLM not appropriate. If 2023 list tone affected, then DLM or TR Cert may be required — consult Rating Technical Lead |
| Mixed or factual and valuation issues? | Scenario 5 — 2026 tone reduced and demolition: as for scenario 1 and 2 | DLM | Transitional relief certificate | Consider confidence in facts and effective date of event subsisting prior to 01 April 2026 |
| Deletions with effect from 1 April 2026 | Scenario 6 — property deleted by notice or on agreement. Circumstances arose before 1 April 2026 | DLM | Not applicable | No data |
| Completion notices | Scenario 7 — date specified before 1 April 2026 | DLM | Not applicable | No data |
| External MCC | Scenario 8 — road works commencing before 1 April 2026 | DLM | Transitional relief certificate | Consider the severity and duration as relating to the 2023 list entry |
| External MCC | Scenario 9 — opening up of competitor business (for example Wetherspoons) before 1 April 2026 | DLM | Transitional relief certificate | Consider the severity and duration as relating to the 2023 list entry |
| Survey corrections | Scenario 10 — survey errors discovered in dealing with 2023 list case (appeal or maintenance), see scenario 1 and 2 | DLM/transitional relief certificate | Transitional relief certificate | Consider confidence in facts and effective date of event subsisting prior to 01 April 2026 |
| Exemptions (including partial exemption) | Scenario 11 — farm office, exemption conceded with effect from 1 April 2026 and facts recently obtained | DLM | Transitional relief for partial exemption only | DLM if Valuation Office is satisfied that prior to 1 April 2026 the facts are the same. If facts at 31 March 2026 unclear then not applicable |
| Exemptions (including partial exemption) | Scenario 12 — special school. Deleted from compiled 2023 list by Billing Authority report and facts recently obtained. Circumstances arose wit effect from 1 June 2025 | DLM | Not applicable | DLM if Valuation Office is satisfied that prior to 1 April 2026 the facts are the same. If facts at 31 March 2026 unclear then not applicable |
| Composites — a property becoming a composite or an increase in amount of non-domestic | Scenario 13 — house becoming partly non-domestic property (for example, part of shop over flat becomes used for storage). 2026 list altered by Billing Authority report, Valuation Office report or agreement of IPP with effect from 1 April 2026 and facts arose before 1 April 2026 | DLM | Not applicable | Ensure Council Tax entry is aligned |
| Composites — a reduction in amount of non-domestic | Scenario 13 — storage above shop converted to include in owner’s flat — 2026 list altered by Billing Authority report, Valuation Office report or agreement of IPP with effect from 1 April 2026 and facts arose before 1 April 2026 | DLM | Transitional relief certificate | Liaise with Council Tax — if inspected for Council Tax and all relevant facts for non-domestic rates confirmed then DLM |