Line4

Solvency UK checker for your PRA returns

For UK insurers that send Solvency UK returns (QRTs) to the PRA. Line4 Check runs every one of the Bank of England's own XBRL validation rules, and 49 checks from its XBRL Filing Manual, on your quarterly and annual returns, solo and group, and the annual return for third-country branches, in XBRL-XML, on the Bank's insurance taxonomy 2.2.0. Your file never leaves your computer.

Live5 Solvency UK returns on taxonomy 2.2.0: all 2,292 of the Bank's XBRL validation rules for these returns, every one matched to Arelle (the open-source reference processor) on the Bank's samples and on synthetic test files, plus the 49 filing checks from the Bank's XBRL Filing Manual v1.0.1.

Drop your Solvency UK return here

One XBRL-XML instance (.xbrl), or a .zip holding just that file, for one of the 5 Solvency UK returns listed below, on the Bank of England's insurance taxonomy 2.2.0. Each file is checked against the Bank's rules for the return its schemaRef names.

Your file never leaves your computer. It is checked inside this browser tab: nothing is uploaded, and nothing from the file is recorded.

What we record

Your file is checked in your browser and never uploaded. This is all Line4 keeps about each check, here and on regulators’ websites that show Line4 Check.

For each check, Line4 records

  • Which return was checked and on which Bank of England taxonomy release, such as the quarterly solo return on 2.2.0
  • The file format: XBRL-XML
  • The kind of result: passed, warnings only, blocking errors, nothing could be checked, or a return not covered
  • The address of the page the check ran on, without anything after a ? or #
  • The date and time
  • Visits and clicks, counted by Vercel Web Analytics without cookies

Never recorded

  • Your file, or any part of it: it is checked in your browser and never uploaded
  • The file name
  • The entity, its LEI or the reporting date
  • Any value or message from the file, or which or how many checks failed
  • Who you are: no name, email, cookie or IP address is kept with the record

If you ask for the report by email, that report (not your file) and your email address are sent to Line4. See the privacy policy.

New to Solvency UK? Solvency UK reporting sets out who files, on which taxonomy, and by when. Got a validation ID back, such as IR_bv0674_01? Every one of the Bank's 2,292 validation rules Line4 Check runs is explained in plain words, with what to do if your return fails it. All 29 returns the PRA lists for insurers are in Line4's library of regulatory returns, in plain English, with who files each one, when and in what format. Filing Solvency II QRTs to a supervisor in the EU or EEA? Use the Solvency II checker, under EIOPA's rules. A check at submission is the first step to real-time supervision. Need premium support or bespoke validation? Contact us.

What Line4 Check checks

The Bank of England publishes its validation rules with each taxonomy release, as XBRL formulas in the taxonomy and in a workbook. The counts here are the rules in the XBRL for each return, less those the Bank switches off in the taxonomy package or on its deny list (last updated 3 October 2026). Each figure comes from the compiled rule files themselves.

Solo undertakings

  • Quarterly solo return (QRS)The Bank's name: Quarterly Solvency II reporting SoloRules run267of 267 · 100%Same as Arelle267 of 267on the Bank's sample and synthetic files
  • Annual solo return (ARS)The Bank's name: Annual Solvency II reporting SoloRules run1,847of 1,847 · 100%Same as Arelle1,847 of 1,847on the Bank's sample and synthetic files

Groups

  • Quarterly group return (QRG)The Bank's name: Quarterly Solvency II reporting GroupRules run213of 213 · 100%Same as Arelle213 of 213on the Bank's sample and synthetic files
  • Annual group return (ARG)The Bank's name: Annual Solvency II reporting GroupRules run425of 425 · 100%Same as Arelle425 of 425on the Bank's sample and synthetic files

Third-country branches

  • Annual return for third-country branches (ARB)The Bank's name: Annual Solvency II reporting Third country branchesRules run696of 696 · 100%Same as Arelle696 of 696on the Bank's sample and synthetic files
All 5 returnsDistinct rules: many apply to more than one return, so the rows add up to 3,448.2,292of 2,292 · 100%
Plus the Bank's filing rulesFrom its XBRL Filing Manual v1.0.1, on every return: what they check.49filing checks

There is no quarterly return for third-country branches in 2.2.0: the Bank deleted it (QRB), as PS13/26 removes third-country branches from quarterly reporting.

Every report carries the same line, for example: “This free check runs all 267 of the Bank of England's XBRL validation rules for quarterly solo returns on taxonomy 2.2.0, each matched to Arelle (the open-source reference processor) on the Bank's sample and on synthetic test files, plus the 49 filing checks from the Bank's XBRL Filing Manual v1.0.1. It is not a substitute for the validation the Bank runs when you submit.”

How we know the results are right

Every one of the Bank's rules that Line4 Check runs was compared with Arelle 2.47.4, the open-source XBRL processor, check by check: the same result and the same number of evaluations. First on the Bank of England's own sample return for each entry point, 3,448 of 3,448 checks (a rule in several returns counts once for each). Then on 72 test files: 30 synthetic returns that fill every cell a return can hold, six for each return, 40 copies of the samples with facts outside the templates, and 2 returns of greyed cells only. There was not one difference, and Arelle evaluates every one of the Bank's rules on at least one of these files.

The Bank fills its samples with random data and says they cannot be assumed to conform to its validation rules, so they fail some. On each sample, Line4 Check fails exactly the rules Arelle fails:

  • Quarterly solo return (QRS)Run on it226Passed193Failed33
  • Quarterly group return (QRG)Run on it174Passed153Failed21
  • Annual solo return (ARS)Run on it369Passed291Failed78
  • Annual group return (ARG)Run on it397Passed340Failed57
  • Annual return for third-country branches (ARB)Run on it632Passed557Failed75

The Bank's annual solo sample fills only part of the return, so 1,478 of the 1,847 annual solo checks have nothing to run on there, in Arelle or in Line4 Check. They run on the synthetic and test files instead, with the same results as Arelle. Two rules the Bank's known issues log has under review run as published, as Arelle runs them: warnings on template IR.22.01 that can fire on valid zeros (issue 198), and IR_bv1768 (issue 233), which the Bank says does not affect reporting outcomes.

The Bank's filing rules

The Bank asks firms to follow its XBRL Filing Manual (v1.0.1, the version its 2.2.0 release note names) for how the instance itself is written. Line4 Check runs 49 of its rules on every return, under the Bank's own numbers: the file name and encoding, the schemaRef and entry point, the filing indicators, the entity identifier (an LEI, FRN or Lloyd's syndicate code), contexts and dates, units and decimals, nil and duplicate facts, and more. A broken MUST rule is an error and a broken SHOULD rule a warning. The results show them in their own card, each in plain words first, then its number: “Bank of England filing rule 2.26”.

Each one was tested on copies of the Bank's samples broken on purpose, 74 test files in all: every file fires exactly the rules it breaks. Arelle has no Bank of England filing rules, but for most of these its EBA or EIOPA filing rules or its XBRL checks report the same problems on those files; the rest follow the manual's own words. The Bank's five samples break no filing rule that is an error. They break three SHOULD rules: they do not name the software that made them (2.26) and have fact ids nothing uses (3.7), all five, and their filing indicators come after the facts (1.6.2), all but the annual solo sample.

The rules checked, by the Bank's numbers: 1.1, 1.4, 1.5.(a), 1.5.(b), 1.6.(a), 1.6.(c), 1.6.1, 1.6.2, 1.6.3, 1.7.(b), 1.7.1, 1.9, 1.13, 1.14, 1.15, 2.1, 2.2, 2.4, 2.6, 2.7.(a), 2.7.(b), 2.8.(a), 2.9, 2.10.(a), 2.10.(b), 2.11, 2.13, 2.14, 2.15, 2.16, 2.16.1, 2.17, 2.18.(a), 2.18, 2.19, 2.21, 2.22, 2.23, 2.24, 2.25, 2.26, 3.1.(a), 3.2.(a), 3.4, 3.5, 3.7, 3.9, 3.10 and 3.11.

Which taxonomy: 2.2.0

The Bank published the Bank of England Insurance Taxonomy 2.2.0 on 2 September 2026. The frameworks it amends and adds (DIS, IR, IMO and MAL) are effective from 1 January 2027, for reporting with a reference date on or after 31 December 2026 (Bank of England). The five returns here are the entry points of its IR framework, and a file names one in its schemaRef, such as http://www.bankofengland.co.uk/data/xbrl/md/fws/insurance/ir/2026-09-02/mod/qrs.xsd. Line4 Check matches that address exactly, so a UK file is never checked against EIOPA's rules, or an EU file against the Bank's.

How it works

  1. 01Your browser downloads the engine and the rulesThe Line4 engine with its XBRL-XML reader is compiled to WebAssembly (492 KB). Only the rules of the return you check are downloaded: the Bank’s quarterly solo rules are 106 KB, its annual solo rules 1,111 KB. Your browser keeps them for next time.
  2. 02Your file is opened on your computerThe XBRL-XML instance is read inside the browser tab, in a background worker so the page stays responsive. Its schemaRef says which return and taxonomy release it is. Nothing is uploaded.
  3. 03Every check runs in momentsEach failed check is listed by template, in plain words, with the value found, the value expected and the Bank’s rule code; broken filing rules come first, in a card of their own. Download it all as a CSV.

What it does not check

  • 139 rules the Bank publishes only in wordsThe Bank’s validations workbook marks them “Include in XBRL = no” and gives no formula, so Arelle cannot run them either: 88 data-type checks on dates, country codes and currency codes, and 51 cell equalities, 48 of them on the claims triangles.
  • The other Solvency UK returnsInternal model outputs (IMO), matching adjustment assets and liabilities (MAL), public disclosure (APS, APG), market risk sensitivities (MRS), special purpose vehicles (SPV), internal model firms (AIS) and the liquidity returns (CFL, CFS, COL, LMR). Line4 Check does not run them yet.
  • Filing-manual rules the file cannot showThe upload rules and the note on ad hoc reporting dates: they are about sending the file through BEEDS or RegData, not the file itself. Rules 1.12, 2.5, 2.6.(a) and 2.8.(b): they need facts the file does not hold. Rules 2.6.(b), 2.18.(b) and (c), 3.2.(b), 3.3 and 3.8: the manual gives no measure to check them against. Rules 1.6.(b) and 2.20: MAY rules, which a file cannot break. Rules 3.1.(b) and (c): they test the currency of an amount against a dimension the manual says insurance returns do not have.
  • Earlier taxonomy releasesFiles built on the Bank’s releases before 2.2.0, for reference dates before 31 December 2026.

Line4 Check is a prototype of the Line4 validation engine, not certified software. Use it to find problems early, and rely on the Bank's own validation for the result that counts.

Questions

What is Solvency UK?

The UK’s rules for insurers, which grew out of Solvency II (the PRA’s papers also say UK Solvency II). Insurance firms send their regulatory returns to the Prudential Regulation Authority (PRA), part of the Bank of England, and Solvency UK applies to all insurance regulatory reporting with reference dates of 31 December 2024 and later. Firms submit the returns through the Bank’s BEEDS portal, as XBRL built on the Bank of England Insurance Taxonomy. Bank of England · Our guide to Solvency UK reporting.

How is it different from EIOPA’s Solvency II?

Same roots, different taxonomy and rules. Insurers in the EU and EEA file on EIOPA’s taxonomy, under EIOPA’s validation rules. UK insurers file on the Bank of England Insurance Taxonomy (now 2.2.0), which uses EIOPA’s dictionary alongside the Bank’s own, with its own templates (codes starting IR, such as IR.02.01 for the balance sheet, where EIOPA’s start S), its own entry points, its own validation rules and deny list, and returns of its own, such as the matching adjustment return (MAL) that is new in 2.2.0. The Bank has told firms not to implement EIOPA’s taxonomy 2.7 or any later release. So each file needs its own publisher’s rules: Line4 Check reads the schemaRef and checks a UK file only against the Bank’s rules. The Solvency II checker.

Which returns can I check?

Quarterly solo return (QRS) (the Bank’s name: Quarterly Solvency II reporting Solo); Quarterly group return (QRG) (the Bank’s name: Quarterly Solvency II reporting Group); Annual solo return (ARS) (the Bank’s name: Annual Solvency II reporting Solo); Annual group return (ARG) (the Bank’s name: Annual Solvency II reporting Group); Annual return for third-country branches (ARB) (the Bank’s name: Annual Solvency II reporting Third country branches), all on taxonomy 2.2.0. Each is one XBRL-XML instance (.xbrl), or a .zip holding just that file. The list above gives the number of the Bank’s rules each one runs.

Is it free?

Yes. There is no account, no upload and no limit on how many returns you check. After a result you can leave your email address to get the report by email, if you want it. For premium support or bespoke validation, contact us at team@line4.ai.

Does my file leave my browser?

No. Your file never leaves your computer. Your browser downloads the Line4 engine (WebAssembly) and the Bank of England’s rules for your return from line4.ai, then opens and checks the file on your own computer. Nothing is uploaded, and nothing from the file is recorded. If you ask for the report by email, only the report you see is sent to Line4, not the file.

What does Line4 record?

For each check: the return checked and its Bank of England taxonomy release, the file format, the kind of result (passed, warnings only, blocking errors, nothing could be checked, or a return not covered), the address of the page it ran on without anything after ? or #, and the time. Never the file or any part of it, its name, the firm or its LEI, the reporting date, any value or message, or which or how many checks failed, and no name, email, cookie or IP address with the record.

Which taxonomy version does it use?

The Bank of England Insurance Taxonomy 2.2.0, published on 2 September 2026. The Bank says the frameworks it amends and adds (DIS, IR, IMO, MAL) are effective from 1 January 2027, for reporting with a reference date on or after 31 December 2026. A file names its taxonomy in its schemaRef (…/insurance/ir/2026-09-02/mod/qrs.xsd for the quarterly solo return on 2.2.0); a file built on an earlier release names another date, and Line4 Check does not check it yet. Release note.

Is this the same as the Bank’s own validation?

No. It is a free check to catch problems before you submit. The Bank runs its validation rules in its own data collection system when you submit through BEEDS, and that result is the one that counts. It can run rules Line4 Check does not, listed on this page under What it does not check.

What do errors and warnings mean?

The Bank’s validations workbook gives each rule a severity for each return: ERROR or WARNING. Line4 Check uses the same severity, return by return. Line4 Check counts failed errors as blocking and failed warnings as non-blocking.

How do you know the results are right?

Every one of the Bank’s rules it runs was compared with Arelle 2.47.4, the open-source XBRL processor, check by check: the same result and the same number of evaluations. First on the Bank’s own sample return for each entry point (3,448 of 3,448 checks), then on 72 test files: 30 synthetic returns that fill every cell a return can hold, 40 with facts outside the templates and 2 of greyed cells only. Not one difference, and every rule is evaluated on at least one of these files. Each of the 49 filing checks was tested on copies of the Bank’s samples broken on purpose. It is a prototype, not certified software.

Does it check the Bank’s filing rules?

Yes, 49 of them, from the Bank’s XBRL Filing Manual v1.0.1 (the version its release note names), under the Bank’s own rule numbers: how the instance itself is written, from its file name, encoding, schemaRef and filing indicators to the entity identifier, contexts, units, decimals and duplicate facts. A broken MUST rule is an error and a broken SHOULD rule a warning, each in plain words, then the rule number. The manual’s other rules cannot be checked from the file itself; they are listed on this page under What it does not check. EIOPA’s and EBA’s filing rules are not the Bank’s, so they are not run.

Sources