Jorge installs air conditioning in Seville with a van and an assistant. Summer 2026 was crazy: €20,000 of taxable base invoiced in the third quarter, €4,200 of VAT charged. The problem is that a construction firm he works with pays at ninety days, and by mid-October Jorge had only been paid invoices worth €12,000. His 303 for the quarter comes to €3,800 (€4,200 of VAT charged minus €400 of VAT paid on his own purchases) and is due on 20 October. He has about €2,300 in the account. This page is about how the 303 is paid and, above all, what to do when the account does not stretch that far.
The payment options, with their real dates
| Payment method | How it works | Until when (Q3 2026) | What to know |
|---|---|---|---|
| Direct debit | You file and the bank charges the amount | File by 15 October | The charge is made on the last day of the period |
| NRC | You pay at your bank, which gives you a code; you enter it when filing | 20 October | Each bank has its own cut-off time that day |
| Acknowledging the debt with a deferral | You file without paying and ask for instalments | 20 October | Not all VAT can be deferred |
| Acknowledging the debt with an offset | You ask for it to be deducted from a refund the tax office owes you | 20 October | Only if you have a recognised credit in your favour |
The NRC is the Número de Referencia Completo, the receipt code a bank issues when it collects tax on the tax office's behalf. For the fourth quarter, whose period ends on 30 January, direct debit usually closes on the 25th. The exact dates each year are checked in the Agencia Tributaria's taxpayer calendar, because when the last day falls on a public holiday they move.
The limit almost nobody knows: VAT already collected cannot be deferred
Here is the trap in the 303. Article 65.2 of the Ley General Tributaria, Spain's General Tax Act, declares that debts for taxes that have to be passed on to customers cannot be deferred, unless it is shown that the VAT charged has not actually been paid. Put plainly: the VAT your clients have already paid you is not yours, and the law does not let you finance yourself with it. The VAT you have not yet collected, if you can prove it, can be deferred.
That changes Jorge's calculation completely:
- VAT charged on invoices already paid: 12,000 × 21 % = €2,520.
- VAT charged on unpaid invoices: 8,000 × 21 % = €1,680.
- Deductible input VAT: €400.
- Part that cannot be deferred: 2,520 − 400 = €2,120. Jorge pays it with an NRC on the 20th. He is left with about €180 in the account.
- Part that can be deferred: the €1,680 on unpaid invoices, proving they have not been collected (the invoices issued, bank statements showing the money has not come in, and any claims made to the client, if there are some).
- Instalments over four months: €420 a month. With late-payment interest of 4 % for the sake of the example: 420 × 0.04 × (1 + 2 + 3 + 4)/12 = €14. Total cost: €1,694.
How the debt is split between what is paid and what is deferred, and which documents the tax authorities accept as proof of non-payment, is checked when the request is processed on the online office. We explain it in more detail in debts that cannot be deferred, and the real calendar of an instalment plan, month by month, in a realistic instalment calendar.
Guarantee and terms
For debts that together do not exceed €50,000, Orden HFP/311/2023 has waived the need to provide a guarantee since 15 April 2023. Automated requests without a guarantee are granted, as a rule, for up to twelve months; for individuals, the 2023 instructions allow up to twenty-four as an administrative practice, not as a right.
Asking to defer the whole 303 without showing that the VAT has not been collected is the quickest way to end up worse off than if you had asked for nothing. When a request filed within the voluntary period is rejected as inadmissible, it is treated as never filed, and the debt has been in the periodo ejecutivo, the enforcement stage, since the day after the deadline, with its surcharge. If you cannot show that your clients have not paid, it is better to pay what you can and find financing for the rest than to file a request that is doomed.
What Jorge will do differently next year
There is a scheme designed for exactly his problem: the régimen especial del criterio de caja, the special cash-accounting scheme for VAT. Anyone who opts into it does not pay the VAT on an invoice until they collect it, subject to a time limit. It has its costs (input VAT is not deducted until the supplier has been paid either, and it affects your business clients, who cannot deduct the VAT on your invoices until they pay you), and above all it has a condition: you must opt in before the year begins, normally in December through Modelo 036, or when you register. It does not rescue the quarter already on top of you. For anyone who works with construction firms that pay late, it is worth running the numbers in November.
The second decision is about cash flow: set aside each month, in a separate account, the 21 % of what you collect. It seems obvious, and it is what gets done least. If you would like us to help you organise your quarters, the self-employed form is the starting point. The guide to Modelo 303 for the self-employed also explains how each box is calculated.
When the 303 comes out in your favour
The flip side of Jorge's problem is the quarter in which you have bought more than you have sold: a new van, tools, a refit of the premises. The 303 comes out negative and there is nothing to pay, but nothing is paid out on the spot either. In the first three quarters of the year, the negative balance can only be offset in the following ones. The refund is claimed on the fourth-quarter 303, in January, and the tax authorities have a period to pay it, after which interest accrues in the taxpayer's favour. Only those registered for monthly refunds can claim every month, and that registration carries its own obligations.
This matters for cash flow: someone who makes a large investment in February may wait a year to see the VAT money. In the meantime, if they owe the tax office anything, that balance in their favour can be used to offset it. Planning large purchases for the end of the year, when it makes sense for the business, shortens that wait.
And one last point for anyone filing a 303 with a refund: the account given must be in the name of the person filing the return. A refund requested to a partner's account or a relative's company account is delayed or rejected, and has to be requested again.
Three payment slips we see every quarter
Setting up the direct debit on the 18th. Direct debit closes before the end of the period. Anyone who tries it late finds they can only pay with an NRC that same day or ask for a deferral.
Paying with an NRC and not filing. The bank takes the money, gives you the code, and the 303 is never sent. The money is with the tax office, but the return is not, and the payment is not applied until the return is filed. Filing the same day you pay avoids the problem.
A returned debit. If there are not enough funds on the day of the charge, the bank returns the debit and the debt stays unpaid, in the enforcement stage, without anyone telling you at the time. It is worth checking your statement on the 21st.