Welsh Ministers have made the Non-Domestic Rating (Chargeable Amounts) (Wales) Regulations 2025 (WSI 2025/1371) under sections 58 and 143A of the Local Government Finance Act 1988. The instrument was made on 17 December 2025 and comes into force on 31 December 2025. It provides the statutory basis for transitional relief following the 2026 revaluation across Wales.
The Regulations apply to chargeable days from 1 April 2026 to 31 March 2029. They cap how quickly non-domestic rates bills can rise for eligible properties, smoothing material increases over two financial years before reverting to full liability in the third year.
Eligibility is tied to a “defined hereditament”. To qualify on any relevant day, the property must appear on the local rating list or the central list on 31 March 2026, on that day, and on every intervening day. If a property is removed from a list, entitlement stops from the effective date of removal; earlier days are unaffected.
Two anchor figures shape the calculation. The base liability (BL) is the charge for 31 March 2026 under section 43 (occupied, local list) or section 54 (central list) of the 1988 Act, annualised by multiplying by 365. The notional chargeable amount (NCA) is the liability that would apply on 1 April 2026 under sections 43, 45 (unoccupied, local list) or 54, also annualised.
Relief only applies where the NCA exceeds the BL by more than £300. In addition, the person who was the ratepayer on 31 March 2026 must be the same person liable on the relevant day, the property must have been occupied on 31 March 2026, and no part-occupation apportionment under section 44A may apply. These conditions target support at continuous occupiers facing substantive increases.
For properties that meet those conditions, the charge for any day is first calculated under sections 43, 45 or 54 and then reduced by a transitional amount. If the reduction would result in a negative figure, the charge is set to zero. Billing authorities apply the calculation on a daily basis and aggregate it in the bill.
The phase-in is fixed in statute. In 2026–27, the bill is reduced by 67% of the increase between BL and NCA. In 2027–28, the reduction is 34% of that same increase. From 1 April 2028 to 31 March 2029, no reduction applies and the standard chargeable amount is payable. The formula for 2027–28 uses 366 days to reflect the 2028 leap year.
Illustration. If BL is £10,000 and NCA is £15,000, the increase is £5,000. In 2026–27, the payable amount is £15,000 minus 67% of £5,000 (£3,350) = £11,650, effectively BL plus 33% of the increase. In 2027–28, the payable amount is £15,000 minus 34% of £5,000 (£1,700) = £13,300, effectively BL plus 66% of the increase. From 2028–29, the full £15,000 applies, subject to any other reliefs or multipliers.
Where the underlying liability falls after 1 April 2026-for example due to a list change, appeal or relief taking effect-the NCA used in the transitional formula resets from the effective date of the change. The calculation also adjusts for the number of days in the financial year in which that change occurs.
Scope and exclusions are clear. The scheme includes hereditaments on the central list as well as local lists, but it excludes properties that were unoccupied on 31 March 2026 and cases where a part-occupation apportionment under section 44A applies. The 2025 Regulations revoke the Non-Domestic Rating (Chargeable Amounts) (Wales) Regulations 2022, replacing the previous transitional arrangements for the new lists.