The Results
| Model | Fully correct | Partly correct | Wrong | Out of date | No answer |
|---|---|---|---|---|---|
| Claude Haiku 5.5 | 8.8% | 41.2% | 42.2% | 4.9% | 2.9% |
| Claude Sonnet 5.5 | 27.5% | 44.1% | 18.6% | 7.8% | 2% |
| Claude Opus 5.5 | 49% | 35.3% | 10.8% | 3.9% | 1% |
| Claude Sonnet 5.5 with web search | 41.2% | 44.1% | 10.8% | 3.9% | 0% |
102 questions each; percentages of answers. “Out of date” means a rule, rate or fee that applied in the past but has since changed.
Where AI Goes Wrong
The 23 questions that at least two models got wrong or out of date, with the right answer and the rule. Open each for an example of the wrong answer.
How much is the hearing fee on the fast track and on the multi-track, and when must it be paid?
The answer: Fee 2.1 is £619 on the fast track and £1,334 on the intermediate track or multi-track. It is paid by the claimant at least 28 days before the trial date (or the Monday of the first week of the trial period) where notice was sent 36 days or more before, and otherwise within 7 days after the notice. If unpaid and no remission applied for, the claim is struck out automatically. (Fees Order Sch 1, notes to fee 2.1; CPR 3.7A1(7))
The error, in short (Claude Sonnet 5.5 with web search): Pay the hearing fee when you file the pre-trial checklist (listing questionnaire)... otherwise pay within 14 days of the court sending notice of the trial date or trial week.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, Claude Sonnet 5.5 with web search. More on this
What is the court fee to appeal a small claims track decision in the County Court in England and Wales, and can I recover costs of the appeal?
The answer: The court fee is £151 for an appeal in the County Court on the small claims track, from 13 July 2026. The small claims limits on recoverable costs apply to the appeal too, though the cost of an approved transcript reasonably incurred can be recovered. (Civil Proceedings Fees Order 2008, Sch 1; CPR 27.14(2))
The error, in short (Claude Sonnet 5.5 with web search): I recall the fee being about £167 when I last saw it
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, Claude Sonnet 5.5 with web search. More on this
What is the court fee in England and Wales for making an application on notice in a civil case where no other fee is specified?
The answer: The current fee is £321 where no other fee is specified.
The error, in short (Claude Sonnet 5.5 with web search): the court fee for an application on notice where no other fee is specified was **£313** in the 2025–26 EX50 fee table
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, Claude Sonnet 5.5 with web search. More on this
Can a defendant in England and Wales get security for costs against a claimant resident in the EU under the current CPR?
The answer: Yes, the condition can be met. Since 6 April 2025 it reads that the claimant is resident out of the jurisdiction, with no exception for Hague 2005 or EU states. Whether an order is just depends on a real risk of obstacles to, or extra burden of, enforcement there. (r.25.27(b)(i); Qatar v Phoenix [2025] EWCA Civ 1300 at [10]–[14]; Bestfort [2016] EWCA Civ 1099 at [73]–[77])
The error, in short (Claude Sonnet 5.5 with web search): Generally no. Residence in the EU is not, on its own, a ground for security for costs... CPR 25.13(2)(a) allows security where the claimant is resident out of the jurisdiction but not resident in a State bound by the 2005 Hague Convention.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, Claude Sonnet 5.5 with web search. More on this
In England and Wales, what are the response deadlines under the pre-action protocol for disease and noise-induced hearing loss claims? Is the defendant's reasoned answer due within three months?
The answer: The defendant must acknowledge within 21 days of the date of posting of the letter of claim, identify all insurers within 30 days of the acknowledgment, and give a reasoned answer within 90 days of the acknowledgment. It is 90 days, not three months. Annex E hearing loss claims likely to suit the fast track, where the first letter of claim was sent on or after 1 October 2023, follow the same timetable. (paras 7.1, 7.2, 7.3, 2.2A and E1)
The error, in short (Claude Sonnet 5.5 with web search): Mostly yes, but the three months runs from the defendant's acknowledgment... Investigation period of up to three months... reasoned answer is due about three months and 21 days after the letter of claim
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, Claude Sonnet 5.5 with web search. More on this
How many days' notice of enforcement must an enforcement agent give a debtor before taking control of goods in England and Wales, and can it be longer?
The answer: From 1 May 2026 the notice must be at least 14 clear days (previously 7), or at least 28 where a debt advice provider asks on the debtor's behalf before the notice period ends, unless the debt is non-eligible business debt. Sundays, bank holidays, Good Friday and Christmas Day do not count. (Taking Control of Goods Regulations 2013 reg 6, as amended by S.I. 2026/366)
The error, in short (Claude Sonnet 5.5 with web search): At least **7 clear days**... notice of enforcement must be given to the debtor not less than 7 clear days before the enforcement agent takes control of the debtor's goods.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, Claude Sonnet 5.5 with web search. More on this
Is a housing disrepair claim by a tenant seeking repairs treated as a small claim in England and Wales?
The answer: Only if the repairs are estimated at £1,000 or less and any other damages claimed are £1,000 or less (CPR 26.9(1)(b)). Otherwise it normally goes to the fast track or a higher track, where costs are assessed because fixed recoverable costs do not apply to disrepair claims (CPR 45.1(4)). (CPR 26.9(1)(b); CPR 45.1(4))
The error, in short (Claude Sonnet 5.5 with web search): On the fast track, the winning party can usually recover fixed recoverable costs.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Sonnet 5.5 with web search. More on this
In England and Wales, what test applies when a defendant applies to set aside a default judgment that was validly entered, and does the Denton approach come into it?
The answer: The court may set the judgment aside if the defendant has a real prospect of successfully defending the claim or there is some other good reason, and must have regard to whether the application was made promptly. The Court of Appeal has held that the Denton tests then apply in full. (CPR 13.3; FXF v English Karate Federation [2023] EWCA Civ 891 at [72])
The error, in short (Claude Sonnet 5.5 with web search): Does Denton apply? Not directly... CPR 13.3 is a self-contained rule with its own criteria... the Supreme Court in Thevarajah v Riordan confirmed that the Mitchell/Denton approach does not govern applications to set aside under Part 13.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Sonnet 5.5 with web search. More on this
Is there still a limitation period for personal injury claims arising from child sexual abuse in England and Wales?
The answer: From 29 June 2026 there is no limitation period for personal injury claims for sexual abuse of someone under 18, including older claims, unless they were settled or decided by a court before then. If brought after the old time limit, the court must dismiss the claim if the defendant shows a fair hearing is not possible. Non-sexual abuse claimed in the same action keeps the 3-year limit and the s.33 discretion. (Limitation Act 1980 s.11ZA, inserted by s.96 Crime and Policing Act 2026; s.11ZB; KHX v Isle of Wight Council [2026] EWHC 1949 (KB))
The error, in short (Claude Haiku 5.5): The Limitation (Child Sexual Abuse) Act 2018 removed it... The 2018 Act disapplied the time limit for personal injury claims where the claimant was a child when the abuse occurred
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5. More on this
Where are the rules for the Stage 3 procedure in the portal claims now found, and what form does the defendant use to acknowledge service in England and Wales?
The answer: The Stage 3 Procedure is in Practice Direction 49F, which replaced PD 8B on 1 October 2023. The defendant files and serves an acknowledgment of service in Form N210B not more than 14 days after service of the claim form. (Practice Direction 49F, paras 8.1 and 11.2)
The error, in short (Claude Haiku 5.5): Stage 3 rules for Portal claims are in Practice Direction 8B ... the defendant acknowledges service using Form N9
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5. More on this
A claim issued after October 2023 is re-allocated from the small claims track to the fast track. Which costs regime applies to the claim?
The answer: For claims issued on or after 1 October 2023 (with conditions for personal injury claims), a claim moved off the small claims track gets the new track's costs as if allocated there from the outset (CPR 27.15). Costs orders made before allocation are not affected (CPR 46.13(1)). (CPR 27.15; CPR 46.13(1))
The error, in short (Claude Sonnet 5.5 with web search): From the date of re-allocation, the fast track FRC regime governs costs... The party does not recover fast track FRC for work done before re-allocation.
Wrong or out of date: Claude Sonnet 5.5, Claude Opus 5.5, Claude Sonnet 5.5 with web search. More on this
Is mediation compulsory for small claims in England and Wales, for example a defended debt claim issued in the county court in mid-2024?
The answer: Under the PD 51ZE pilot, a claim issued on or after 22 May 2024 that would normally be a small claim, where the only remedy claimed is a specified sum of money and it is not a road traffic accident or personal injury claim, is referred to the HMCTS Small Claims Mediation Service once every party has filed its directions questionnaire, without anyone's agreement. The pilot runs to 6 April 2027. (Practice Direction 51ZE; CPR 26.6 as modified)
The error, in short (Claude Sonnet 5.5 with web search): It runs until 21 May 2026.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Sonnet 5.5 with web search. More on this
Do weekends and bank holidays count when calculating CPR time limits in England and Wales, for example a 14 day period?
The answer: Only periods of 5 days or less leave out Saturdays, Sundays, bank holidays, Christmas Day and Good Friday. Longer periods count every day, but a filing at court whose period ends on a day the court office is closed is in time on the next day it is open. (CPR 2.8(4) and 2.8(5))
The error, in short (Claude Sonnet 5.5 with web search): CPR 2.8 contains no general rule moving the deadline to the next working day. If the last day is a Saturday, you should usually act by the preceding Friday.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Sonnet 5.5 with web search. More on this
If a defendant refuses to pay a claimant's reasonable pre-action costs, can the claimant issue court proceedings solely to recover those costs, or is that an abuse of process in England and Wales?
The answer: It is not an abuse of process. In Alphabet (UK) Ltd v AXA Insurance UK Plc [2026] EWHC 674 (SCCO) Costs Judge Brown held that where a defendant refuses to pay costs properly incurred before action, a claimant may issue proceedings to recover them. (Alphabet (UK) Ltd v AXA Insurance UK Plc [2026] EWHC 674 (SCCO))
The error, in short (Claude Haiku 5.5): A claimant cannot usually issue a standalone claim just to recover pre-action costs. Doing so risks being struck out or criticised as an abuse of process.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5. More on this
In England and Wales, how far does QOCS protect a personal injury claimant from enforcement of the defendant's costs order, and has that changed recently?
The answer: In personal injury claims, costs orders against the claimant are enforceable without permission only up to damages and interest ordered for the claimant or, in claims issued from 6 April 2023, damages, interest and costs ordered or agreed. Strike-out (CPR 44.15) or permission under CPR 44.16 lifts that cap. (CPR 44.14)
The error, in short (Claude Haiku 5.5): Costs orders against the claimant can be enforced without permission only up to the total of the damages and costs the claimant has been awarded in the proceedings. (and the answer says fundamental dishonesty is under r.44.16 with no cap, and that strike-out under r.44.15 only permits enforcement 'to the extent just')
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5. More on this
Is there a time limit for enforcing a judgment or costs order in England and Wales, for example after six years?
The answer: Enforcement is not time-barred, but a writ or warrant of control needs the court's permission once six years have passed since the judgment or order. The Limitation Act s.24(1) bars a new action on a judgment after six years, not execution, and no interest more than six years in arrears can be recovered. (CPR 83.2(3)(a); Limitation Act 1980 s.24; Lowsley v Forbes [1999] 1 AC 329)
The error, in short (Claude Haiku 5.5): Enforcement methods such as charging orders, third-party debt orders, or bankruptcy or winding-up proceedings are also subject to the permission requirement after six years
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5. More on this
How is the issue fee worked out for a money claim in England and Wales where the sum claimed including interest is over £10,000, and how is it rounded?
The answer: Take the sum claimed including interest, multiply by 5% and round down to the nearest penny. For example, a claim of £12,345.79 pays £617.28 because 5% is £617.2895 and the fee is rounded down. The 5% band covers claims over £10,000 and up to £200,000.
The error, in short (Claude Haiku 5.5): the result is rounded up to the nearest £5 (e.g. £617.25 rounded up to £620)
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5. More on this
Does London weighting apply to fixed costs in England and Wales, and if so which ones and by how much?
The answer: Only to the fixed costs in Sections IV, VI, VII and VIII of Part 45, and only where both conditions in CPR 45.3 are met. Those fixed costs, excluding disbursements, then rise by 12.5%. (CPR 45.3; Practice Direction 45 Section II)
The error, in short (Claude Sonnet 5.5): The current regime ... doesn't, as far as I know, apply a general geographic London weighting.
Wrong or out of date: Claude Sonnet 5.5, Claude Opus 5.5. More on this
In England and Wales, does interest keep running on a County Court judgment debt while an attachment of earnings order is in force?
The answer: No. No interest accrues while an attachment of earnings order is in force. Taking enforcement proceedings also stops interest on a County Court judgment carrying interest, unless they produce no payment at all. (County Courts (Interest on Judgment Debts) Order 1991 art 4(1) and art 4(3))
The error, in short (Claude Haiku 5.5): Yes. Interest keeps running on a County Court judgment debt while an attachment of earnings order (AEO) is in force.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5. More on this
In England and Wales, when must the fast track pre-trial checklist be filed, and what happens if no party files one?
The answer: It is due by the date in the notice of allocation, which cannot be more than 8 weeks before the trial date or start of the trial window. If no party files one, the court orders it within 7 days, failing which the claim, defence and any counterclaim are struck out. (CPR 28.4)
The error, in short (Claude Haiku 5.5): each party must complete it and file it within a fixed period, normally 14 days from the date the court sent it
Wrong or out of date: Claude Haiku 5.5, Claude Opus 5.5. More on this
In England and Wales, can the court award more than the fixed costs on issue, judgment and enforcement in a debt claim, and has a recent case dealt with this?
The answer: Yes. The rules apply unless the court orders otherwise, so the court may award more, for example where enforcement is fought hard rather than being simple debt collection (Chedington Events Ltd v Brake [2024] EWHC 384 (Ch)). (CPR 45.16(1); Chedington Events Ltd v Brake [2024] EWHC 384 (Ch), paras 20 to 21)
The error, in short (Claude Haiku 5.5): The court's discretion under CPR 44 to award costs as it sees fit does not generally let it award more than the fixed amount; exceptions are narrow and only where the rules expressly permit.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5. More on this
Can a company apply to set aside a statutory demand served on it in England and Wales?
The answer: No. The set-aside procedure is for individuals. A demand on a company must tell it that it may apply to the court for an injunction restraining the creditor from presenting or advertising a winding-up petition. (IR 2016 r.7.3(1)(k))
The error, in short (Claude Haiku 5.5): Yes. A company served with a statutory demand in England and Wales can apply to the court to set it aside... within 18 days of service of the demand.
Wrong or out of date: Claude Haiku 5.5, Claude Sonnet 5.5. More on this
For guideline hourly rates in England and Wales, does the applicable band depend on the court hearing the case or on where the fee earner works? And which band do Liverpool and Bristol firms fall into?
The answer: The band follows the office the fee earner works from, or is mainly attached to, not the court hearing the case. Liverpool and Bristol are National 1. (Guide to the Summary Assessment of Costs, para 31)
The error, in short (Claude Haiku 5.5): Guideline hourly rates are tied to the location of the court where the proceedings are being conducted. A London firm handling a case in Liverpool is generally assessed at the Liverpool (provincial) rate.
Wrong or out of date: Claude Haiku 5.5, Claude Opus 5.5. More on this
Results by Topic
| Topic | Questions | Haiku 5.5: wrong or out of date | Sonnet 5.5: wrong or out of date | Opus 5.5: wrong or out of date | Sonnet 5.5 with web search: wrong or out of date |
|---|---|---|---|---|---|
| Court fees | 4 | 100% | 100% | 75% | 75% |
| Other | 10 | 60% | 50% | 40% | 30% |
| Fixed costs and small claims | 12 | 41.7% | 58.3% | 25% | 16.7% |
| Limitation | 4 | 50% | 50% | 25% | 0% |
| Court forms and procedure | 12 | 50% | 25% | 16.7% | 8.3% |
| Funding and retainers | 1 | 100% | 0% | 0% | 0% |
| Part 36 and settlement offers | 8 | 50% | 12.5% | 12.5% | 0% |
| Housing disrepair | 7 | 42.9% | 14.3% | 0% | 14.3% |
| Interest | 7 | 42.9% | 14.3% | 0% | 14.3% |
| Time limits and service | 13 | 53.8% | 7.7% | 0% | 7.7% |
| Detailed assessment | 12 | 33.3% | 16.7% | 0% | 8.3% |
| Budgets and summary assessment | 10 | 20% | 0% | 10% | 20% |
| Clinical negligence | 2 | 50% | 0% | 0% | 0% |
Topics with few questions move a lot with one answer: read them as pointers, not ratings.
What It Means for Firms
- Treat an AI answer on fees, rates or anything changed since 2023 as a lead to check, not an answer.
- Watch for confident errors on time limits: several answers stated a rule the wrong way round.
- Ask for the rule and check it in the CPR, the Practice Direction or the fee order itself.
- Our free costs tools and guides give the rule for each answer, and every source they cite is re-checked monthly.
How We Did It
- Questions. 107 questions were drawn from the reviewed FAQ answers in our guides and tools, each answer tied to its rule, statute or judgment, spread across the topics solicitors ask about and weighted towards points people commonly get wrong, including recent changes. After review, 5 were dropped because the right answer is arguable, leaving 102.
- Models. Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, Claude Sonnet 5.5 with web search, through Anthropic’s API on 25 and 26 October 2026, with no system prompt, at high reasoning effort.
- Marking. A separate model compared each answer with the reference answer and key points. Every answer marked wrong or out of date for the strongest model was checked again against the rule text.
- Limits. One provider’s models, tested once, on a question set aimed at points that trip people up; a broader set of easier questions would score higher. Consumer apps add instructions and search, so they can answer differently.
The questions dropped after review, and why
- How long does a receiving party have to commence detailed assessment proceedings in England and Wales, and is that period a target or a limit? Whether the CPR 47.7 three months is a "target" or an "outside limit" is a matter of characterisation: late commencement is not barred (CPR 47.8 sanctions), so answers calling it a target were graded wrong on wording rather than law.
- Is a solicitor who acts for themselves in a costs dispute in England and Wales treated as a litigant in person, or can they recover profit costs as if represented? Answers reaching the right outcome (a solicitor acting through their practice recovers profit costs) by a different classification (Chorley exception rather than CPR 46.5(6)(b) as read in Halborg) were graded wrong; the classification point is arguable.
- A claimant has discontinued without needing the court's permission. How long does the defendant have to apply to set the notice of discontinuance aside in England and Wales? Whether the court can extend the CPR 38.4(2) 28 days under its general power in CPR 3.1(2)(a) is arguable; answers saying an extension may be sought were graded wrong.
- In England and Wales, if a claimant obtains a judgment at least as advantageous as their own Part 36 offer, what additional consequences can the court order? The reference gives the CPR 36.17(4)(d) additional amount as a flat 10%; the rule applies 10% up to £500,000 and 5% above, capped at £75,000, so answers giving the tiered figure were graded wrong against a simplified reference.
- In England and Wales, can a Calderbank offer still be accepted after the other side has rejected it, and how long does it stay open if it has no time limit? Answers giving the reference points (contract, reasonable time, rejection ends the offer) with hedged wording were graded wrong; the verdict rests on phrasing, not a legal error.
Open Data
Download every question, reference answer, key point, rule and verdict (CSV). Free to reuse under the Creative Commons Attribution 4.0 licence: please credit DMD Costs. More datasets on our open data page.