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KYC quality assurance for remediation: sample size and confidence

KYC quality assurance in a remediation is a stated sample behind every batch approval: zero errors in 40 files supports 95% confidence that fewer than 7.2% of the batch is wrong. This guide shows the arithmetic, how to define an error, what one error should do to a batch, and how KYC Remediation puts the confidence on the approval screen.

Updated · 12 min read

KYC quality assurance in a remediation means checking a sample of each batch of remediated files, by someone other than the person who prepared them, against a written definition of an error, and stating what the result supports. The arithmetic is simple and often misread: if a checker samples 40 files at random and finds no errors, the bank can say with 95% confidence that fewer than 7.2% of the batch is wrong, and no more than that. Remediation QA is hard because batches are large, errors are rare but costly, and a sample that is too small, or an error definition that misses the failures examiners look for, approves bad work with a clean record. Botminds' KYC Remediation states the sample, the result and the confidence on every batch it sends to a checker.

The examples come from a fictional sample institution, Norrell Federal Credit Union, approving batches in its programme on 38,400 acquired member files. The arithmetic is ours and shown in full; enforcement facts link to the regulators' orders.

What a clean sample supports, at 95% confidence

20files

sampled with no errors: fewer than 13.9% of the batch is wrong

40files

sampled with no errors: fewer than 7.2% is wrong

59files

needed with no errors to say fewer than 5%

300files

needed with no errors to say fewer than 1%

Our arithmetic: the one-sided 95% upper bound on the error rate when no errors are found in n randomly sampled files is 1 − 0.05^(1/n), close to 3 ÷ n, the ‘rule of three’ described by Hanley and Lippman-Hand (JAMA, 1983). Treating the batch as large is conservative.Source: Hanley and Lippman-Hand, JAMA 1983

What does KYC quality assurance mean in a remediation?

In a remediation, KYC quality assurance is the control that lets a bank approve thousands of files without re-reading each one, by sampling them and stating what the sample shows. It answers the question a board or an examiner will ask about any batch: how do you know these closures are right? "A senior person looked at some of them" is not an answer; "a different person sampled 40 at random, stratified by source, against this error definition, found none, so fewer than 7.2% are wrong at 95% confidence, and one error would have sent the stratum back for full review" is.

Regulators ask for the control by name. The OCC's 2024 order against TD Bank required, among the elements of the new CDD programme, "a quality control process to ensure CDD policies and procedures are adhered to" (OCC AA-ENF-2024-77, Article XII (p)). Examiners test in the same way: the FFIEC's CDD procedures tell them to "select a sample of customer information" and judge whether it supports the customer's risk profile (FFIEC examination procedures, CDD). A remediation's QA should be at least as rigorous as the sample the examiner will draw.

How many files should you sample in KYC QA?

Sample enough files that a clean result rules out the error rate you could not accept. If the bank's tolerance for a batch is "fewer than 10% wrong", 30 clean files will show it; "fewer than 5%" needs 59; "fewer than 1%" needs about 300. The size of the batch hardly matters once it is in the thousands, which surprises people: 40 clean files say the same thing about a batch of 4,000 as about a batch of 40,000.

Bigger samples buy tighter bounds, slowly: the error rate a clean sample rules out

10 files, no errors
under 25.9%
20 files, no errors
under 13.9%
30 files, no errors
under 9.5%
40 files, no errors
under 7.2%
59 files, no errors
under 5.0%
100 files, no errors
under 3.0%
300 files, no errors
under 1.0%
Our arithmetic: one-sided 95% upper bound, 1 − 0.05^(1/n), for a large batch sampled at random. The fictional sample programme in KYC Remediation uses 20 for batches under 500 files and 40 for larger batches and every beneficial owner batch.

The curve is why most programmes settle on a few fixed sizes rather than a percentage of the batch. A 1% sample of a 300-file batch is three files and proves almost nothing; a 1% sample of a 30,000-file batch is 300 and proves more than most programmes need. The sample programme's choice, 20 files for small batches checked by a quality reviewer and 40 for large and beneficial owner batches checked by the BSA officer, puts the tighter bound where the volume and the risk are.

What zero errors in 40 files proves, and what it does not

Zero errors in 40 files proves that the batch's error rate is very unlikely to be above 7.2%: if it were 7.2%, a random sample of 40 would come back clean only about one time in twenty. It does not prove the batch is perfect, and it cannot tell a batch with no errors from one with a few. A batch with a 2% error rate passes a 40-file sample about 45% of the time; a batch at 5% still passes about 13% of the time.

How often a batch passes a clean-sample test, by its true error rate

True error rate in the batchChance 20 sampled files are all cleanChance 40 sampled files are all clean
1%82%67%
2%67%45%
5%36%13%
7.2%22%5%
10%12%1.5%
Our arithmetic: (1 − error rate) raised to the sample size. A clean sample screens out bad batches; it does not certify good ones.

That is the right way to read a QA result: as a screen, not a certificate. It is also why the sampling is only half the control. The other half is upstream: rules that stop bad closures being proposed at all, such as never closing when two sources disagree. When a single error does turn up, the arithmetic changes sharply: one error in 40 lifts the 95% upper bound to about 11.3%, which is why a failed sample should trigger a full review of its stratum, not a shrug.

What counts as an error in KYC QA?

An error in KYC QA is any closure that the evidence in the file does not support under the programme's standard, plus any breach of a control the programme treats as absolute. The definition has to be written before sampling starts, because a checker who decides case by case what counts will find what they expect. It should distinguish errors that fail the file from defects that are fixed in place.

An error definition for remediation QA: what fails a file, and what is fixed in place

FindingCounts asWhy
A value in the record that its cited source does not showErrorThe closure is unsupported, whatever else is right
A file closed when two sources disagreeErrorThe disagreement was the thing to resolve
A missing value scored as low risk, or filled from someone’s recollectionErrorMissing data must be collected, not assumed
A beneficial owner or control person not screenedErrorScreening is part of the closing rule
A message sent on a restricted file, or one hinting at monitoringErrorA tipping-off risk, whatever the file’s state
The wrong reason code on a correct decisionDefect, fixed in placeThe evidence supports the outcome
A source cited correctly but at the wrong page or lineDefect, fixed in placeA checker can still find it
Our suggested definition. The first five rows match what the fictional sample programme in KYC Remediation treats as a failed file; one such error returns its stratum for full review.

Missing is not low: the USAA lesson for error definitions

The most damaging KYC error is not a wrong value but a missing one treated as a value. FinCEN's 2022 order against USAA Federal Savings Bank found that "Management would arbitrarily assign risk sub-scores of 1 or 2 (on a 10-point maximum scale) for risk factors where member data was missing", and that "of approximately six million customer-risk scores, not a single customer received a high-risk score of 5.5 or higher" (FinCEN Consent Order No. 2022-01). Each score might have passed a QA check that asked only whether the arithmetic was right.

The lesson for a remediation QA plan is to test for absence. A sampled file should be checked for whether each value the standard needs is present and sourced, not only whether the values present are correct. In a remediation that re-rates customers, a rating proposed before the file's other gaps close should count as an error, because it repeats exactly the failure the order describes; that is why ratings come last in the KYC remediation process.

Stratify the sample, and decide what one error does

A stratified sample draws from each source or type of file in proportion, so a problem confined to one source cannot hide behind clean files from the others. On the sample programme, the BSA officer's 40 files from a 3,982-file beneficial owner batch were drawn by loan type: 12 equipment loans, 11 commercial real estate, 10 operating lines and 7 vehicle loans. An error in one stratum returns that stratum, not the whole batch, for full review.

The checker’s sample: 40 files, stratified, with each file’s sources side by side

KYC Remediation beneficial owner cohort viewed as BSA officer Ruth Abernathy. Batch B-1022-BO of 3,982 files shows the sample drawn: prepared by the agents, maker an analyst at 9:31 AM, checker Ruth Abernathy with sample drawn. A note says the agents re-read each sampled file’s sources side by side, any source can be opened, the batch is accepted only with no errors, and one error sends its stratum back for full review. Sampled files are listed with their loan type and certification and report dates, each marked as matching. A line reads 40 of 40 match their sources, 0 errors; with no errors in 40, there is 95% confidence that fewer than 7.2% of the batch has an error.
The fictional sample programme in KYC Remediation. The confidence statement appears before the checker approves, not after.

Two other rules belong in the plan. The checker must not be the maker, however small the batch. And the sample must be drawn by the system or by the checker, not chosen by the maker. A QA plan that writes down the sample size per batch type, the strata, the error definition, the rule for one error and who checks which batches can be read by an examiner in five minutes, which is the point.

A KYC QC checklist for every remediation batch

  1. The maker and the checker are different people

    No exceptions for small batches or busy weeks.

  2. The sample size is set by batch type, not chosen per batch

    For example 20 below 500 files, 40 above and for every beneficial owner batch.

  3. The sample is stratified by source or file type

    So a fault in one loan system or one cohort cannot hide.

  4. The error definition is written down first

    Including missing values treated as values, and tipping-off breaches.

  5. Each sampled file is read against its sources

    The value in the record, the line in the document, the rule it meets.

  6. One error has a stated consequence

    The stratum goes back for full review, and the cause is fixed before the next batch.

  7. The result and its confidence are recorded with the approval

    With the reason, so the audit trail shows what the checker relied on.

Our checklist, as applied on the fictional sample programme in KYC Remediation.

KYC document review: what the checker actually reads

A checker in KYC document review reads the cited source, not the analyst's summary of it. For a beneficial owner closure, that is the signed certification with its owners, percentages, control person and signature date; the owners' identification images; and the state annual report listing the same people. For a reply from a customer, it is the uploaded document and the customer's answers next to the value proposed for the record.

A quality reviewer reads a customer’s reply with each proposed value beside its source

KYC Remediation review screen for fictional member Marisol Vega: three gaps, each with how it closed and its source. A renewed Idaho driver’s licence uploaded in digital banking whose name, date of birth and address match; three questions answered on purpose and expected activity, about $4,200 a month in, no international payments; and an OFAC screening with no match. The member record before and after lists ID, purpose of the account, expected activity and risk rating. The decision panel names the maker and offers approve as checker, return with reason or edit a value, with a reason dropdown.
The fictional sample programme in KYC Remediation. Approving writes the values to the core banking system, each with its source.

The speed of the read is what makes a 40-file sample practical. If evidence has to be fetched from three systems for each sampled file, a checker will sample fewer files or read them less carefully; if each source opens from the file with the lines used highlighted, a clean read of 40 files is a morning's work. European supervisors make a similar point for automated onboarding: the EBA's guidelines list "sample testing" and "manual reviews" among the means a firm should use to monitor the adequacy of its solution (EBA/GL/2022/15).

KYC quality control vs quality assurance vs KYC audit

Quality control checks each batch before it is approved; quality assurance tests whether the programme's controls work across batches; a KYC audit is the independent third line, internal audit or an examiner, testing both. In job titles the terms blur, and a KYC quality control analyst often does what this page calls QA. The distinction matters for the plan, because each line needs its own evidence.

Three lines checking one remediation, and what each needs from the file

LineWhat it checksWhat it needs
Quality control (first line)Each batch before approval, on a stated sampleCited sources, the error definition, the sampling rule
Quality assurance (second line)Whether QC works: error trends, returned strata, maker and checker patternsEvery batch’s sample, result and reason in one place
KYC audit (third line) and examinersBoth, independently, on their own sampleAn export of files, sources, approvals and the audit trail
Our summary. Examiners sample customer information under the FFIEC’s CDD procedures; internal audit and the supervisory committee or board follow their own plans.

How KYC Remediation states the confidence behind each batch

KYC Remediation makes the sample a setting and the confidence a line on the approval. Batches under 500 files go to a quality reviewer with a sample of 20; larger batches and every beneficial owner batch go to the BSA officer with a sample of 40, stratified by source; one error returns its stratum for full review; these are settings an administrator can change only with a second administrator's approval. For each sampled file the agents re-read the sources side by side, and the checker can open any of them.

On the sample programme's beneficial owner batch, 40 of 40 matched their sources, the BSA officer approved with the reason "Sample passed with no errors", and 3,982 files were written to the core banking system with their evidence. The design target is that 100% of closed files cite the record used and carry a maker and a different checker. To see the sample, the reasons and the audit trail together, start from KYC Remediation; to see how QA fits the staffing of a whole project, read a KYC remediation project with agents.

Questions people ask

What does a KYC quality control analyst do?

A KYC quality control analyst checks other people's files against the standard, usually on a sample, and records whether each passes and why. In a remediation they act as the checker on batches the analysts have approved as makers. On the fictional sample programme, quality reviewers check batches under 500 files on a sample of 20.

What sample size do regulators require for KYC QA?

No US rule sets one. Orders such as TD Bank's require a quality control process, and examiners draw their own samples. The bank should choose sizes it can defend with arithmetic: 40 clean files support fewer than 7.2% errors at 95% confidence, and 59 clean files support fewer than 5%.

Does the batch size change the sample I need?

Very little once a batch is in the thousands. The bound depends on the number of files sampled, not the share; 40 clean files say about the same for a batch of 4,000 as for 40,000. For small batches, sampling without replacement makes the bound slightly tighter, so the large-batch figure is conservative.

What should happen when the QA sample finds an error?

Return the affected stratum, or the batch if it was not stratified, for full review, and find the cause before approving the next batch. One error in 40 lifts the 95% upper bound to about 11.3%, so a batch with a failed sample cannot be approved on that sample.

Will an examiner rely on our QA sample?

Not instead of their own. Examiners draw their own sample of customer information under the FFIEC's CDD procedures, and they will also look at whether the bank's quality control caught what it should have. A QA record that states each batch's sample, result and reason makes that review faster and the bank's account of its own controls credible.

KYC Remediation.
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