Andrés is an electrician in Córdoba and works almost always as a subcontractor for two construction firms. His 303, the quarterly VAT return, for the second quarter of 2026 came to €4,600, and in mid-July he did not have it. He hesitated between two options that seemed equivalent to him: file it without paying or simply not file it and wait until he had the money. He asked us which was less bad. They are not remotely equivalent, and the difference between them, with its figures, is the heart of this page.
Route one: file and do not pay
If Andrés files the 303 on time, acknowledging the debt but without paying it, the return is correct and the tax authorities know how much he owes. On the day after the deadline, the debt enters the periodo ejecutivo, the enforcement stage, and the surcharges in article 28 of the Ley General Tributaria, Spain's General Tax Act, apply:
- If he pays before being served with the providencia de apremio (the formal demand for payment): enforcement surcharge of 5 %. 4,600 × 0.05 = €230. Total: €4,830.
- If he pays within the period the demand grants: reduced collection surcharge of 10 %. €460. Total: €5,060.
- If he lets that period pass as well: ordinary collection surcharge of 20 %, €920, plus late-payment interest and, if there is a seizure, its costs. Total: €5,520 plus interest.
Route two: do not file
If he does not file, there is no acknowledged debt and, for a while, nothing visible happens. But the construction firms declare what they pay him, and the cross-check between their returns and Andrés's 303s arrives. When it does, it comes as a formal request or a check, and from then on there is no surcharge but an assessment, interest and a penalty.
The penalty for failing to pay is calculated on the tax due. When the tax exceeds €3,000 and there is concealment (and the law treats not filing the return as concealment when the hidden debt is significant), the offence is serious, with a minimum penalty of 50 %:
- Minimum penalty: 4,600 × 0.50 = €2,300.
- With the 30 % reduction for accepting the assessment: €1,610.
- With the 40 % reduction for prompt payment on top: €966.
- Total in the best case: 4,600 + €966 + late-payment interest from 21 July.
The two routes side by side
| Scenario | Cost on top of the €4,600 | What can be negotiated |
|---|---|---|
| Files without paying and pays before the demand | €230 | Deferral, even in the enforcement stage |
| Files without paying and pays after the demand | €460 | Deferral |
| Files without paying and does not react | €920 + interest + costs | Little: seizures are under way |
| Does not file and is assessed (minimum penalty, all reductions) | €966 + interest | The reductions require acceptance and payment |
| Does not file and disputes the penalty | €2,300 + interest, depending on the appeal | The appeal |
The lesson is uncomfortable but clear: not being able to pay is a cash-flow problem; not filing is an offence problem. How the penalty is graded and when the reductions are lost is set out in the guide on the penalty and its reductions.
What really worries a subcontractor
Here is what almost nobody tells you, and in Andrés's case it weighs more than the surcharges. The Ley General Tributaria, in its article 43, allows anyone who contracts or subcontracts works or services forming part of their main activity to be made secondarily liable for their subcontractors' debts for taxes passed on (VAT) and withholdings relating to that work. The way a contractor protects itself is to ask its subcontractor for a specific certificate of being up to date with its tax obligations.
With a 303 unpaid in the enforcement stage, Andrés cannot obtain that certificate. And a construction firm that does not receive it has a very clear incentive to stop calling him. The same happens with any grant, with public-sector contracts or with some kinds of financing: they all require you to be up to date. An unpaid bill of €4,600 can cost a client worth €60,000 a year in invoices.
The other silent effect is offsetting. If Andrés is owed a refund (on income tax, on another quarter), the tax authorities apply it automatically to the debt in the enforcement stage. Many self-employed people discover their debt that way: waiting for money that never arrives.
If you do not have the money on the 20th, file the 303 anyway and choose to acknowledge the debt or, better still, request in the same step a deferral of the part relating to invoices you have not collected. VAT you have collected cannot be deferred, but a 5 % surcharge on that part is infinitely better than a 50 % penalty on the whole thing. Not filing is never the cheap option, even if for a few months it looks like it.
Already in the enforcement stage: what a deferral stops and what it does not
Many self-employed people come to us when the debt is already in the enforcement stage, sometimes with a frozen account. You can still request a deferral or instalments, with the same guarantee rules: none needed below €50,000. But it is worth knowing what that request achieves and what it does not. Filed in the enforcement stage, the law allows the tax authorities to start or continue the collection procedure while they decide, although they must suspend the sale of any assets already seized until they do. In other words: the request does not undo a seizure of an account that has already taken place, nor does it guarantee that another will not arrive while it is being processed.
The surcharge already accrued (the 5 %, 10 % or 20 %) does not disappear either: it is deferred along with the debt. And the rule on collected VAT still stands: the part relating to VAT your clients have already paid you cannot be deferred, whatever stage the debt is at. That is why, in the enforcement stage, the strategy is usually to pay the non-deferrable part as soon as possible and split the rest into instalments, proving which invoices are still unpaid.
If the seizure has already been made on your account, what the bank holds back is applied to the debt. Whatever remains after covering it is released. If the amount held relates to salary or a benefit, there are seizure limits that protect part of it, and it is worth proving this to the bank and to the tax authorities as soon as possible.
One last, less technical point: the sooner you contact the tax authorities at this stage, the more room there is. A debt of a few thousand euros, with a reasonable instalment request and proof that clients have not paid, can usually be sorted out without major trouble. What complicates things is silence, which the authorities can only read one way.
What Andrés did
He filed the 303 on 18 July acknowledging the debt. One of the construction firms owed him two progress payments; he showed that the VAT on those invoices had not been collected and asked for that part to be paid in instalments. He paid the rest in September with the 5 % surcharge. He kept the certificate of being up to date and both clients. If you are in a similar position and the debt is already at a more advanced stage, the self-employed form helps us see where you stand and how much room is left.
Further reading: the guide on deferring a debt from a regularisation covers the case where the debt already comes from a tax check, and the one on debts that cannot be deferred sets out which part of the VAT cannot be paid in instalments.