RSUs in Spain. In Spain an RSU is not a legal category: it is a contractual promise to which rules written for something else are applied. The characterisation comes out of your plan document, not out of the name of the instrument, and that is where two colleagues with the same grant end up with two different returns.
Priya is an engineer who came from Bangalore to Madrid in 2024, hired by a tech company, and filed Modelo 149 on time to opt into the article 93 regime (the special regime for workers posted to Spain, known as the Beckham regime). Her company withholds 24% of her salary and she understood that this was all there was to it. She did not file Modelo 151, the annual return under that regime, for 2025, whose deadline ended on 30 June 2026. At the end of September, a colleague asks her what her return came out at and she discovers that she did not file one.
The oversight can be fixed and, in Priya's case, it is not expensive. But there are two things worth checking before filing: whether it showed an amount to pay or a refund, and whether that year there was any income the payroll did not pick up.
There is no threshold: under the article 93 regime you always file
In ordinary IRPF (Spanish personal income tax), many employees are not obliged to file if they do not exceed certain limits. Under the special regime that is not the case: the Agencia Tributaria's instructions for Modelo 151 provide no exemption threshold, and anyone in the regime files for every one of the six years the regime lasts, whether the result is a payment, a refund or zero.
The 24% withholding the company applies is a payment on account, not the final tax. The return is what checks whether that 24% covered everything, and in many cases it does not, precisely because of what happened to Priya.
The income the payroll did not see
In 2025, restricted stock units from the US parent company worth 30,000 euros vested for Priya. The parent delivered them directly, and the Spanish subsidiary did not include that amount in the payroll or make any payment on account. Under the article 93 regime, employment income obtained anywhere in the world is taxed, so those shares are employment income taxed at 24%. How RSUs are treated under this regime is in stock options and RSUs under article 93.
| Item | Amount |
|---|---|
| 2025 salary | 140,000 euros |
| Shares vested in 2025 | 30,000 euros |
| Total employment income | 170,000 euros |
| Tax at 24% | 40,800 euros |
| Withholdings made (24% of 140,000 euros) | 33,600 euros |
| Amount to pay | 7,200 euros |
Priya's recargo, calculated
The deadline ended on 30 June 2026. If Priya files on 25 September without having received any request, the recargo in article 27 of the Ley General Tributaria (the surcharge for filing late unprompted) applies:
- Full months of delay counted from 1 July: July and August. September is not complete. That makes 2.
- Surcharge: 1% plus 1 point per full month, 3% of 7,200 euros = 216 euros.
- If she pays the full amount within the deadline of the surcharge assessment, or at the same time as she files, it is reduced by 25%: 162 euros.
- Below twelve months there is no late-payment interest.
Priya pays 7,200 euros plus 162 euros. If she waits until October, the surcharge goes to 4%; if she waits for the Agencia Tributaria to cross-check the information the parent company sends and write to her, the recargo disappears and is replaced by a penalty of 50% to 150% of the tax. The difference between moving in September and not moving is several thousand euros.
If you are in a similar situation and are not clear which income that year fell within the return, the Beckham regime form asks you for what is needed to review it.
If it had shown a refund
Suppose Priya had had no shares and her company had withheld too much, for example because of a mistake in one month. Her 151 would show a refund. In that case there is no recargo, because no amount was left unpaid, and filing late does not make her lose the refund: she has four years from the end of the deadline to claim it.
What she does lose is time. The tax authority has six months from filing to make the refund without paying interest. Filing in September instead of April delays the payment by half a year.
It is a mistake we see often: someone who realises late goes into Renta Web, finds their draft return and files it, because it is the quickest thing to do. But anyone in the article 93 regime does not file with Modelo 100, the ordinary income tax return, but with the 151, with its fixed rate and its own rules. Filing the 100 does not meet the obligation and creates a new problem: a return that will have to be cancelled or rectified.
How a late 151 is filed, step by step
- Gather the withholding certificate from the Spanish company, the details of the vestings sent by the broker or the parent company, and any other Spanish-source income for the year, such as account interest or dividends.
- Check which foreign income stays out. Dividends from Indian shares or interest on an account in Bangalore are not included while the regime lasts.
- Prepare the 151 for the tax year in the Agencia Tributaria's electronic office. There is no "late filing" box: it is filed just as during the campaign, and the tax authority assesses the surcharge afterwards.
- Pay the tax when filing, with an NRC (the payment reference code your bank issues), in order to keep the 25% reduction of the surcharge. Payment in two instalments of 60% and 40% is only available during the campaign.
- Wait for the surcharge assessment, which arrives weeks later, and pay it within its deadline.
Can an oversight cost you the regime?
It is the question that causes the most anxiety, and the answer is reassuring: filing the 151 late is not among the causes that make you lose the regime. The regime is lost by giving it up, by exclusion when the requirements stop being met or by the six tax years running out. All of that is in leaving the article 93 regime.
What can happen is that a prolonged oversight, added to other data, leads the tax authority to review whether the regime was being applied correctly from the start. Filing on time, even if late, is also the way not to give grounds for that review.
Forgetting Modelo 149, the form used to opt into the regime, is another matter. That one has a deadline of six months from registration with the Seguridad Social (Spanish social security) and cannot be filed outside it. If that is what was forgotten, there is no 151 possible: you are taxed under ordinary IRPF. We explain it in the deadline and documents for the 149.
Details that usually go unnoticed
The shares may carry a second tax. If Priya worked in India for part of the vesting period of her RSUs, India may claim the right to tax part of them. The deduction for double taxation of employment income obtained abroad has its own limit under this regime: 30% of the part of the gross tax corresponding to that income. It is worth calculating before filing.
The year 2024 also deserves a look. If the parent company already delivered shares to her in that first year and they were not declared, the 151 for 2024 also needs a supplementary return, with its own surcharge, higher because it has been overdue for longer.
The company has its part. The Spanish subsidiary should have taken into account the shares the parent company delivered to its employees. That does not change what Priya owes, but it is worth telling human resources so that the 2026 payroll correctly picks up the next vestings and the problem does not recur next year.
And a general warning: all of the above holds as long as no communication from the Agencia Tributaria has arrived. If one has, the order of the steps changes and it is worth reading the letter calmly before filing anything.
What people ask us about a forgotten Modelo 151
Should I wait and see whether they ask me for the Modelo 151?
No. With Modelo 151, when it is filed late, the recargo in article 27 of the Ley General Tributaria goes up one point for each full month of delay, and after twelve months it becomes 15% plus interest. But that is not the expensive part: the moment a request arrives the recargo disappears and what opens is penalty proceedings. The difference between moving today and waiting for them to move is usually thousands of euros.
Does the 24% apply to everything I earn?
No. It applies to employment income up to 600,000 euros; above that, the rate goes up. And capital gains and investment income follow their own scale.