Record Retention Clocks for a Small UK Lab: 3, 6 and 40 Years

Which UK statutes set how long a small laboratory must keep purchase, VAT, COSHH and hazardous-waste records, when does each clock start, and which record serves more than one regime?

There is no single answer to how long a small UK laboratory must keep its records. There are at least three: six years for company and VAT records, three years for a hazardous-waste register, and forty years for certain health and exposure records under the COSHH Regulations.

Each period is set by a different instrument and starts from a different event. The practical task is to build a retention table that says, for every record you hold, which clock applies and when it started. Where one document serves two regimes, you keep it for the longer.

Why retention is a table, not a number

Advice that says "keep everything for six years" is correct for the accounts and wrong for the rest. It is the number most people have heard, because accountants repeat it, and it quietly under-covers the records that matter most for safety.

The reverse error also happens. A lab manager who has read about the forty-year COSHH period may decide to keep every invoice for forty years. That is storage cost and a data-protection question with no legal reason behind it.

A table avoids both. It has one row per record type, a column for the governing instrument, a column for the event that starts the clock, and a column for the date it can be disposed of. The rest of this article fills in those columns.

Company and accounting records: six years

For a limited company, GOV.UK says to keep accounting records for 6 years from the end of the last company financial year they relate to ^[1]. The records meant here are the ones that explain the accounts: money received and spent, assets, debts, year-end stock, and the supporting documents. Receipts, orders, delivery notes, invoices, contracts, bank statements and correspondence all count as supporting records.

The guidance lists four reasons to keep them longer: a transaction that spans more than one accounting period, an asset the company expects to last more than six years, a Company Tax Return that was sent late, and an HMRC compliance check that has already started ^[1]. A balance-sheet item such as a freezer or analytical instrument bought for a longer working life is the usual trap in a laboratory. Its purchase record belongs on the longer clock.

The guidance also states a penalty: HMRC can fine a company £3,000 for failing to keep accounting records ^[1]. If records are lost or destroyed, the instruction is to recreate them as well as possible and tell the Corporation Tax office straight away.

A sole trader or researcher working outside a company has a different set of rules for self-assessment records. Those are not covered here, and the correct source is the HMRC guidance for the relevant tax.

VAT records: six years, and what counts as the VAT account

HMRC's VAT record-keeping notice says VAT records should generally be kept for at least 6 years ^[2]. The notice names the business records to keep: bank statements, cash books, purchase and sales invoices, credit and debit notes, orders, delivery notes and relevant correspondence.

It also requires a VAT account. That is the audit trail linking your business records to each VAT return, showing output tax, input tax and any adjustments. There is no prescribed format. A spreadsheet or a field in accounting software is acceptable provided someone could follow it back to the source documents ^[2].

Two details matter to a laboratory that imports. First, the notice says some documents, such as the C79 import VAT certificate, must be kept in their original form ^[2]. Second, a scanned image of a VAT invoice can replace the paper original if it carries all the required details, unless another purpose requires the original. The notice also says that most VAT-registered businesses must keep their VAT account digitally in compatible software, and that copying and pasting between programs does not count as a digital link ^[2].

If six years of storage causes serious problems or undue expense, the notice allows a business to ask HMRC about a shorter period for some records ^[2]. It does not allow you to decide that yourself.

COSHH: forty years for health records, and what is not one

COSHH regulation 11 requires an employer to keep a health record for each employee under health surveillance, and to keep it available for at least 40 years from the date of the last entry made in it ^[3]. The clock therefore runs from the last entry, not from the date the employee joined or left.

The important point is who is under health surveillance. Regulation 11 applies it where an identifiable disease or adverse health effect is reasonably likely from the exposure and there are reliable techniques to detect it, or where the exposure is to a substance listed in Schedule 6 during a listed process ^[3]. Many small laboratories have no employee under surveillance at all, in which case there is no health record to keep. That determination comes from the COSHH risk assessment, not from a general assumption.

HSE's guidance describes a health record as a legal document recording the outcome of surveillance. It holds the worker's details, the hazards they have been exposed to, and whether they remain fit to continue that exposure. It should not hold confidential medical information unless the worker gives written consent ^[5].

Regulation 10 sets a second pair of periods for monitoring records. A monitoring record that represents the personal exposures of identifiable employees is kept for at least 40 years from the last entry. Any other monitoring record is kept for at least 5 years ^[4]. An air-sampling record for a fume cupboard is the second kind. A record tied to a named person is the first.

There is one more duty that small employers overlook. If an employer stops trading, regulation 11 requires them to notify HSE in writing and make all health records they hold available to it ^[3]. A laboratory that closes should plan for those records before it closes, not after.

The hazardous-waste register: three years

For waste producers in England, GOV.UK says to keep records, which it calls the register, for 3 years, at the premises that produced or stored the waste ^[6]. The register comprises one copy of each consignment note, the consignee returns from the business that received the waste, and related documents such as carrier schedules and records of rejected loads. If any document is inaccurate or incomplete, you keep a record of the missing information.

The location requirement is the unusual part. Six years of accounts can be held at an accountant's office. A waste register is supposed to be at the premises that generated the waste. Scanned copies held centrally are a sensible backup, but they do not replace the register at the site.

Waste rules differ between England, Wales, Scotland and Northern Ireland. The GOV.UK page cited here is the English position, and a laboratory elsewhere in the UK should read the guidance of its own regulator.

Lot and certificate records: no statute, longest clock

No UK statute fixes a retention period for the lot number, certificate of analysis or supplier documentation attached to a research reagent used in a laboratory. That does not make the record optional. It means you set the period yourself, by reference to what the record supports.

A certificate and lot record supports three things. It is evidence for the purchase (an accounting record). It is the identity record for the material in any experiment that used it (a scientific record). If the material was a hazardous substance handled by employees, it is part of the story a COSHH assessment tells. The longest of those is the one that decides your retention. Where a record only supports the purchase, six years is enough. Where it underpins published or reported work, the period should follow your institution's research-data policy, which is often longer. For the structure of a traceability record, see documentation and batch traceability.

When one document serves two regimes

The rule is short: keep the document for the longer period. A supplier invoice for a hazardous reagent is an accounting record on the six-year clock. If your COSHH assessment cites that same document as the source of the safety data sheet version in force on the day of purchase, it is also supporting a record that may sit on a longer clock.

The practical way to apply this is to decide, once, which clock a document type belongs to, and to write that into the retention table. People should not be deciding it box by box when a file is archived.

• Purchase invoice: six years, longer if it supports a capital asset or a pending HMRC check.
• Import documents, including any C79 certificate: six years in the VAT file, original form where required.
• Safety data sheet version cited in a COSHH assessment: keep with the assessment, on the assessment's clock.
• Health record, where surveillance applies: at least forty years from the last entry.
• Personal exposure monitoring record: at least forty years from the last entry.
• Waste consignment note: three years, at the producing premises.

Digital copies and originals

The sources cited here are not uniform on this point. HMRC's VAT notice accepts a scanned image of an invoice in place of the paper original when all the VAT details are present, but keeps certain documents, including the C79, in original form ^[2]. The company-records guidance does not address digital copies at all ^[1]. The waste guidance requires the register at the premises ^[6].

Where a source is silent, the cautious course is to keep the original for the full period and treat the scan as a convenience copy. That is a policy choice, not a statement of what the law requires.

What to do next

Write the table. List every record type your laboratory holds, assign each one a clock from the sources above, and note the start event. Put a disposal date in the file, not in someone's memory.

Then check the three cases that cause trouble: assets that outlast six years, any employee for whom a health record exists, and the closing arrangements for health records if the business ever stops trading. Re-read the cited pages before relying on the periods, because retention rules are amended and each source is dated as published in 2025.