How to Prepare Your Supplier Invoices Before Handing Them to Your Accountant

Most articles on this topic tell you to "stay organised" and "send everything on time". That is advice, not a procedure. What follows is a procedure: a six-point check you run on every invoice before it goes in the folder, the arithmetic that tells you what your current handover actually costs, and the one rule that decides whether a piece of paper is a deductible invoice or an expensive souvenir.

Start with the number, because it reframes the whole task. Ardent Partners' 2025 *Accounts Payable Metrics That Matter* benchmark puts the average fully-loaded cost of processing a single invoice at $9.40, with best-in-class teams at $2.78 — and the gap comes largely from how clean and complete the document is when it lands. You are not a 10,000-invoice AP department, but the ratio scales down. If you handle 120 supplier invoices a quarter and burn four minutes on each one — finding the PDF, renaming it, answering your accountant's question about it — that is eight hours per quarter. A full working day, four times a year, spent on filing.

The good news: most of those eight hours disappear if you fix the document *once*, at the moment it arrives, instead of three months later when nobody remembers what it was.

The six-point check that decides whether an invoice is deductible

In Spain, article 6 of the invoicing regulation (Royal Decree 1619/2012) lists what a full invoice must contain. Your accountant is not being fussy when they bounce one back — a document missing these fields is not legally an invoice, and the input VAT on it is not safely deductible. Check each one as the invoice arrives:

Number and, where applicable, series — correlative within its series.
Date of issue (and the date of the transaction, if different).
Full legal name of both parties — the supplier's and yours. Not the trading name. Not "the office".
Tax ID (NIF/VAT number) of the issuer and, for deduction, of you as the recipient.
Description of the goods or services, with unit price before VAT and any discounts.
Tax base, VAT rate, VAT amount shown separately, and any withholding (IRPF) where it applies.

Run that list in ten seconds per document. Anything that fails it goes back to the supplier this week, not in October — a corrected invoice is easy to obtain while the supplier still remembers the job, and near-impossible to chase after a quarter has closed.

The ticket trap: the mistake that quietly costs you real money

This is the single most common leak, and it is invisible until an inspection. A simplified invoice — the till receipt from the petrol station, the hardware shop, the restaurant — legally exists, but by default it does not entitle you to deduct the VAT. To deduct, the simplified invoice must carry the additional details in article 7.2 of the same regulation: your NIF and address, and the VAT charged shown separately.

The practical consequence: every time you accept a plain receipt without asking the cashier to add your tax details, you are donating the VAT. On a €200 purchase at 21%, that is €34.71 of input VAT you will never recover — and if you do that twice a week, it is roughly €3,600 a year. Ask at the counter, before you pay. Nobody can fix it afterwards.

If you are unsure whether an expense is worth chasing, our breakdown of the deductible input VAT you lose every quarter has the categories where most SMBs leak the most.

The handover pack: what your accountant actually needs

Accountants do not want "the folder". They want a set of files they can post without opening a conversation. Three rules cover 90% of the friction:

One invoice, one file. Not a 40-page PDF with everything scanned together. Not three invoices photographed in the same image. If a single invoice spans several pages, those pages go in one file — and only that invoice.

A file name that is a database row. Use `YYYY-MM-DD_supplier_total.pdf` — for example `2026-07-14_iberdrola_142-30.pdf`. This sorts chronologically by default, makes duplicates obvious at a glance, and lets your accountant find a specific document without asking you.

Original digital files, not photos of screens. If the supplier emailed a PDF, send the PDF. A photo of a monitor showing a PDF loses text, gains glare, and forces manual re-typing. Photograph only what exists solely on paper — and then photograph it flat, in daylight, with all four corners in frame.

One more, often ignored: send the invoice, not the payment. A bank transfer receipt proves you paid; it does not prove what you bought, and it does not carry a VAT breakdown. It is not a substitute for an invoice.

Monthly, not quarterly — and what the delay actually costs

Sending everything in the last week before a filing deadline is the default habit, and it is the expensive one. Two reasons, one soft and one with a price tag.

The soft one: your accountant cannot chase a missing or defective invoice in 48 hours. Sent monthly, an incorrect document has weeks to be replaced and still lands in the right quarter.

The priced one: if incomplete records push you into filing late, article 27 of the Spanish General Tax Law applies a surcharge of 1% plus 1% for each full month of delay, rising to 15% plus late-payment interest once twelve months have passed. On a €4,000 VAT bill, three months late is €160 you paid for being disorganised.

Block a recurring 30-minute slot on the same day each month — say the 5th — and send that month's batch. If August or holiday cover is your bottleneck, we wrote a survival plan for closing the quarter short-staffed.

The decision rule for an invoice that arrives late

This is where people either panic or file an unnecessary amendment. The criterion is simple.

Under article 99 of the Spanish VAT Act, the right to deduct input VAT can be exercised in the period in which you incurred it or in any later period, as long as four years have not passed from when the right arose — provided the invoice is properly recorded in your VAT registry books. So a June invoice that surfaces in October is not lost. In the overwhelming majority of cases you simply record it and deduct it in the current quarter. You do not amend a filed return, and you do not throw the invoice away.

The exception worth flagging to your accountant: an invoice for a prior financial year affects your corporate income tax or IRPF profit, not just VAT. Hand those over separately with a note, rather than dropping them into the current pile.

And before anything gets booked, check it is not already there. Duplicates arrive routinely — the supplier emails the invoice, then the driver hands you a paper copy, then a statement reminder shows up. Our guide on catching duplicate invoices before you book them covers the checks that work.

Five things that make your accountant email you back

Illegible photos — cropped edges, shadow across the total, a thumb over the tax base.
No supplier context — an unnamed "Servicios varios" line for €1,800 with no explanation of what it was for.
Mixed personal and business expenses in the same batch, with no flag.
Missing credit notes. If a supplier issued a rectifying invoice, send both documents together or the numbers will not reconcile.
Foreign supplier invoices dropped in silently. Intra-EU purchases usually need reverse-charge treatment and the supplier's valid VAT number. Flag them.

One correction on the calendar, while you are at it

If you have read that Spain's Verifactu invoicing-software requirement hits in 2026, that date moved. Royal Decree-Law 15/2025, published in the BOE on 3 December 2025, pushed the deadline to 1 January 2027 for corporate income tax payers and 1 July 2027 for everyone else, including self-employed workers under IRPF. It is worth knowing precisely, because it affects the *issuing* side of your invoicing software — not the supplier invoices you receive, which is what this article is about. The full picture is in our Verifactu explainer.

Turning the handover into a two-minute routine

Once the check above is habit, the remaining work is pure data entry: reading the tax base, VAT, total, date, supplier and tax ID off each document and getting them into a spreadsheet or your accounting software. That part is worth automating.

The approach that survives contact with a real team is the one that requires no new app and no training: the moment an invoice arrives, forward it to a WhatsApp number, and get the fields back as structured data. Whoever is holding the paper — the site manager, the person at the counter — can do it without logging into anything. If you run a practice on the receiving end, WhappScan for accounting is built around exactly that flow: clients send, you receive clean rows.

The order matters, though. Automating extraction does not fix a receipt with no NIF on it. Fix the document first, automate the typing second.

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