How to keep your business books in Spain without knowing accounting

What the law requires, depending on your legal shape

The first surprise is a pleasant one: Spanish law does not ask the same of everyone, and it asks surprisingly little of the most common setup.

If you are an autónomo (self-employed) under estimación directa simplificada, the simplified direct assessment regime most people start in, you are not required to keep double-entry accounts. Your obligations are libros registro, record books: one for income (the invoices you issue), one for expenses (the invoices you receive) and one for investment assets (equipment and other long-lived purchases). As a VAT taxpayer you also keep the VAT record books for invoices issued and received. It sounds solemn, but a record book is essentially an ordered, numbered list of invoices with their dates, taxable bases, rates and VAT amounts.

If you run an SL (sociedad limitada, the Spanish limited company), the bar rises: double-entry bookkeeping under the Plan General de Contabilidad (PGC, the Spanish accounting standards), with a libro diario (journal) and a book of inventories and annual accounts, books filed with the Registro Mercantil (the Commercial Register), and annual accounts (balance sheet, profit and loss account and notes) approved and deposited every year. Plus the same VAT record books.

The practical takeaway: an autónomo can keep proper records with discipline and a simple tool; an SL needs a system that does real accounting, whether that is software that automates it or a professional who runs it.

Double-entry bookkeeping, in plain words

Double-entry bookkeeping is an idea more than five centuries old that survives for one reason: it works. There is only one rule: every movement is recorded twice, because money that moves always leaves one place and arrives at another. The two entries are called debe and haber, debit and credit, and each pair forms an asiento contable, an accounting entry. The libro diario, the journal, is simply the chronological list of all the entries of the year.

An example with an invoice of 1,000 euros plus 210 euros of VAT (the 21% rate): you record that your client owes you 1,210 euros and, at the same time, that you earned 1,000 euros of income and owe 210 euros of VAT to Hacienda, the Spanish tax office. When the client pays, another entry: money arrives in the bank and the client stops owing you.

That double recording produces the system's most useful property: the debit total must always equal the credit total. If it does not, the books do not balance, and that is not a matter of opinion: it is mathematical proof that something is missing or was recorded wrongly. A well-kept double-entry ledger polices itself, which is why banks and the tax office trust balanced accounts far more than a single-column spreadsheet.

The monthly habit that prevents quarter-end panic

Quarter-end panic is not caused by the tax form: it is caused by reconstructing three months of paperwork in one afternoon. The antidote is a monthly habit of three gestures, half an hour well spent:

• Save every invoice the moment it exists. The ones you issue and the ones you receive. A PDF filed in its folder (or uploaded to your tool) the same day is worth hours of archaeology in October. If you have not issued one yet, start on the right foot with our guide to your first invoice.
• Record expenses on the spot. Ask for an invoice, photograph it or save the PDF, and log it that same day with its date, taxable base and VAT. An expense recorded the day it happens never gets lost; one you plan to note down later vanishes with astonishing ease.
• Reconcile the bank once a month. Reconciling means going through the statement and checking that every movement has its document: every receipt, an issued invoice; every payment, an invoice or a supporting document. Whatever does not match gets solved now, while you still remember what it was.

With this habit, the quarter becomes a formality: the data is already complete and ordered, and it only needs to flow into whichever modelo (tax form) is due. Without it, every deadline is a pop quiz, and pop quizzes get failed.

Which documents to keep, and for how long

Golden rule: keep everything that justifies a number in your books. In practice:

• Invoices issued and received: always. To deduct an expense you need an invoice with your details on it; a till receipt without your NIF (tax ID) does not support a VAT deduction, because the rules only accept as proof an invoice that meets the requirements of the invoicing regulation (RD 1619/2012). Ask for a full invoice, or a simplified one that includes your NIF and address and the VAT amount shown separately. What you can deduct, and under which conditions, is covered in our guide to deductible expenses.
• Bank statements and proof of payments and receipts.
• Contracts, payroll records if any, and the tax forms you filed, with their filing receipts.

For how long? For tax purposes, the general rule is the 4-year limitation period of article 66 of the Ley General Tributaria, the Spanish General Tax Law. If you operate as an SL, the Código de Comercio (Commercial Code, article 30) additionally requires keeping books and supporting documents for 6 years. The practical rule that never fails: keep everything for 6 years.

Digital storage is valid: a PDF you received is an electronic original, and keeping it that way is compliant as long as it stays legible and easy to locate. If an invoice arrives on paper, the prudent move is to keep the paper as well as the scan.

The five classic first-year mistakes

Five slips repeat themselves in almost every first year, and all five can be avoided for free:

• Mixing your personal account with the business one. The number one mistake. Every personal purchase in the business account is a movement you will have to explain, and every business expense paid with your personal card is an expense you will probably forget to deduct. A separate account fixes it at the root.
• Leaving everything for the end of the quarter. Data quality collapses when three months are reconstructed from memory. And if the backlog ends in a late filing, the late-filing surcharge kicks in: a flat 1% plus 1% for each complete month of delay. What to do in that case is covered in our guide to missed deadlines.
• Deducting with till receipts. Without an invoice carrying your details, no VAT deduction survives an inspection.
• Forgetting issued invoices. Invoices are numbered consecutively within each series; if number 7 is missing between 6 and 8, the gap shows. Record every invoice the moment you issue it.
• Not keeping bank statements. They are the backbone of reconciliation and the first thing requested in an inspection. Download them every month; banks do not keep them accessible forever.

Software, a gestor, or both?

There is no single answer, but there is a clear rule of thumb.

Software is enough when your activity is simple: services, a handful of invoices a month, no employees and no exotic operations. The tool guides you, the record books come out of what you register, and you keep control and understanding of your own business. The rules are pushing in that direction anyway: under Verifactu, invoicing software must generate verifiable records, applying from 1 January 2027 for SLs and 1 July 2027 for autónomos.

You need a gestor (tax advisor) when payroll appears, when international operations get complex, when you run several activities at once or, simply, when you do not want to spend a single hour on it. A good professional costs less than one big mistake.

The mixed route is what works best for most people: you record the day-to-day in the software (invoices, expenses, bank) and a professional reviews the year-end close, the odd cases and the fine-print decisions. You pay for judgement, not for typing.

That is the philosophy kontora is built on: double-entry accounting happens by itself underneath while you just invoice and upload expenses; every operation generates its entry, the record books and the box-by-box drafts of your VAT, withholding and informative forms come out of that, and the app warns you before every deadline and watches the BOE for you. Filing is still done by you, with the work already prepared.

Frequently asked questions

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