The Unbroken Chain: A Digital Link Health Check for UK VAT Records

For many UK micro-businesses, VAT compliance appears settled: invoices are raised in one application, expenses are tracked in a spreadsheet, figures are passed to an accountant, and the return is filed through Making Tax Digital software. Each step may be digital in isolation, yet the chain between them can still break. HMRC's requirement is not merely that the return is submitted digitally; the records that support it must be maintained with digital links. Manual re-keying is the most common weak point. The purpose of this health check is to prove the chain, not to assume it.

What a digital link actually requires

Under Making Tax Digital for VAT, digital records must be kept in compatible software, and data must flow between software products without manual intervention. A digital link can take the form of an API connection, a CSV import, a spreadsheet formula within the same file, or a bridging tool. The practical test is whether data is transferred or exchanged without someone reading a figure and typing it into another system. Exporting a CSV and importing it into filing software is generally a digital link if no manual re-entry occurs. Copying a column from an email into a return template is not. The distinction matters because HMRC may ask for evidence of the process, not only the final return.

Map the flow from sale to submission

Start with a single VAT quarter. List every system that touches the numbers: sales invoicing, point-of-sale, bank feed, purchase ledger, expense application, payroll where relevant, accountant's working papers, and the MTD filing software. For each handoff, note the method of transfer: API, CSV export and import, bridging software, shared drive, email, or manual entry. Mark any step where a person retypes, copies and pastes, or reformats figures by hand. That is the first candidate for a broken link. The map should be simple enough to show on one page and specific enough to name the file or connection involved.

Test the evidence, not the intention

A digital link is only as good as the evidence that it operated. For the chosen quarter, trace three transactions: one sale, one credit note, and one purchase. Follow each from the original record to the relevant VAT return line. Keep screenshots or exports showing the transfer method, the date, and the software involved. If the accountant receives a spreadsheet by email and imports it into filing software, the email alone is not the link; the import step is. If a spreadsheet is used to calculate box figures, check that formulas reference the transaction data directly rather than a manually entered total.

Where the chain usually breaks

Common gaps include sales exported to CSV and then totals typed into a return template; purchase invoices entered in one application and then re-keyed into a spreadsheet; accountant adjustments made outside the digital record and manually added at filing; and bank transactions categorised in a spreadsheet that is later retyped into software. A change of adviser can expose these because new working papers may not preserve the original transfer method. HMRC enquiries may also ask for the audit trail. None of these gaps necessarily means the figures are wrong, but they weaken the claim that the records are MTD-ready.

A fix list for micro-businesses

1. Replace manual re-keying with an import or API connection where the software supports it.
2. Where a CSV import is used, save the exported file and the import log for the quarter.
3. Keep a short process note naming each system and handoff.
4. Restrict spreadsheet adjustments to formulas that pull from the digital record, and document any journal.
5. Ask the adviser to confirm, in writing, how data reaches the filing software.
6. Run the three-transaction trace each quarter, not only at year end.

Before HMRC asks

The point of this review is not to create paperwork for its own sake. It is to make the digital chain visible and repeatable. A micro-business that can show an unbroken route from invoice to return is in a stronger position if HMRC makes contact, if a new accountant takes over, or if software changes. The exercise should take less than an afternoon for a single quarter; the fix list may take longer, but it is better done now than during a compliance check. In 2026, with MTD for VAT well established, the standard is not just digital filing but a digital record that can be followed.