Automating invoicing and collections in your business

> Declaration of interest: BAI Business offers an invoicing and payments solution and publishes this article. It is signed by Héctor Redondo, CEO and founder of BAI Business. This is not tax advice: confirm your case with your adviser.

Today I want to talk about how to automate invoicing and collections in your business, which is where many managers lose hours every month and, worse, money they have already earned.

Automating invoicing means the invoice comes out of the data you already hold on the customer, with its number and its registration, and the payment notice goes out by itself when the invoice falls due. Three things can be automated without risk: creating the invoice from the customer file, sending it with a link to pay and chasing on the dates you set. Three others are better left by hand: deciding whether to forgive a debt, how to treat a long-standing customer who is late, and checking that the amount is right.

What to automate and what to leave by hand

Task	Automate it	Leave it by hand
Creating the invoice	Yes: it comes from the customer file with its data and the next sequential number	Checking the amount and the lines before closing it
Sending it	Yes: by email, with the link to pay	A special case, such as an invoice with conditions agreed separately
Collecting	Yes: card payment from the invoice itself, and the payment is recorded by itself	A bank transfer you do not recognise
Chasing	Yes: reminders on fixed dates, each firmer than the last	The call to an important or delicate customer
Forgiving or negotiating	No	Always: it is your decision, not a rule's
Expenses and monthly summary	Yes: recording the receipt, the fixed expenses and the summary	Looking at the summary once a month, for more than filing it

The rule I use: automate what you do the same way every time and leave by hand what depends on who you are doing it to.

What deadlines and amounts the law sets

Law 3/2004, which fights late payment in commercial transactions between businesses, says this (consolidated text from the BOE):

• Payment term: if you have not agreed a date or a term, the debtor has thirty calendar days from receipt of the goods or provision of the service, even if the invoice reached them earlier (article 4.1).
• Agreed maximum: the parties can extend the term, but never beyond 60 calendar days (article 4.3).
• When to invoice: the supplier must get the invoice to the customer before fifteen calendar days have passed from the actual receipt of the goods or the service (article 4.1).
• Late-payment interest: whatever the contract says and, if nothing is agreed, the European Central Bank rate on its latest main refinancing operation plus eight percentage points, set every half-year (article 7.2).
• Collection costs: in addition, a fixed 40 euros for each debt in arrears, plus compensation for proven collection costs above that amount (article 8.1). The debtor does not pay it if the delay is not their fault (article 8.2).

Being clear about this helps you write the reminder: it is not a request for a favour, it is a reminder of an agreed date.

E-invoicing and Verifactu

Two different rules with two calendars, often mixed up. The dates change and I keep them, with their sources, in the guide to Verifactu and e-invoicing. I do not repeat them here so as not to leave you with an outdated figure.

How to set up the reminders

This is my own judgement, not a rule. A sequence of four notices is usually enough:

1. Three days before the due date: a friendly reminder with the invoice and the link to pay. Many unpaid invoices are simply forgotten.
2. On the due date: the same notice, shorter.
3. A week later: firmer, with the agreed date and the amount.
4. Two weeks later: no longer an email; you call.

Change the days to suit your sector. What does not change is that the reminder always goes out, without depending on you remembering or on you feeling awkward about chasing.

Imagine a small accountancy practice that invoices about twenty clients every month, at 30 days, and chases by phone when it remembers. It never knows how many invoices are overdue until it looks at the bank. With an automatic notice every time, what is left by hand is the call in step four, and only for whoever has not replied. (An invented example, not a real customer.)

What we have built at BAI

According to what we publish on our website, in BAI you prepare the invoice from the customer file, as a pro forma if you like, and close it as the final invoice, with its sequential number for the year. With Verifactu switched on, the invoice carries its QR code and its record is sent to the Tax Agency, for which you authorise BAI with it. Every invoice carries its link to pay by card; if it falls due unpaid, your customer receives reminders on the days you choose, each firmer than the last. If they pay by bank transfer, you note the payment on the invoice and the reminders stop. Expenses go in at once (you paste the text of a receipt and artificial intelligence fills in date, amount and category), the monthly summary shows income, expenses, balance and the VAT to settle, and at the end of the quarter you export a tidy file for your adviser, with whom you can keep working.

What to do now

Pull out the overdue invoices from your last quarter and note how many days each customer took to pay. With that number, decide your sequence of notices. If you want to see how we do it, there is invoicing and payments. And if you want to understand what is worth automating in the rest of the business, start with what it means to automate a business.

How we checked this

The deadlines, the interest and the 40 euros come from the consolidated text of Law 3/2004 in the BOE, read on 11 October 2026 (its last published update is dated 1 October 2014). I have not checked whether there are reform proposals in progress. What I say about BAI comes from the published page of the solution. The reminder sequence is my own recommendation, not a source. I wrote it with the help of artificial intelligence from those sources; I sign it myself.

Sources

• Law 3/2004 of 29 December establishing measures to combat late payment in commercial transactions, articles 4, 7 and 8, consolidated BOE: https://www.boe.es/eli/es/l/2004/12/29/3/con (accessed on 11 October 2026).
• Guide to Verifactu and e-invoicing for small businesses: guide.
• Description of BAI's solution: published page Invoicing and payments.