Offsetting Prior-Year Losses in Corporate Tax: How Tax Loss Carryforwards Work

When a company closes a financial year with losses, that tax loss doesn’t simply disappear: it becomes a tax loss carryforward that the company can offset against profits in future years, reducing its Corporate Tax bill. It’s one of the most useful — and most misunderstood — mechanisms in Spanish SME taxation, because it combines a generous benefit (it never expires) with offset limits and substantiation requirements that need to be clearly understood before applying it on Form 200.

How much loss can be offset each year?

The general rule under Corporate Tax is that losses generated in prior years can be offset with no time limit: unlike other tax mechanisms, the right to offset them doesn’t lapse simply because years have gone by. What does exist is a quantitative limit on how much can be applied in any given year: as a general rule, the offset cannot exceed 70% of the taxable base prior to that offset (and before applying the capitalization reserve, where applicable). However, the law itself carves out an important exception so as not to penalize small businesses: in all cases, up to one million euros can be offset, even if that amount exceeds 70% of the base. In practice, this means most SMEs with moderate carryforward losses can apply them in full as soon as they return to profit, without ever hitting the percentage cap.

For large companies with a high net turnover, the law tightens the applicable percentage (reducing it below the general 70% once revenue exceeds certain thresholds), precisely because their taxable base is large enough that the one-million-euro cap stops being relevant. If your company’s turnover is above those thresholds, it’s worth checking the exact percentage that applies for the year before calculating the offset, since it isn’t the same for every company.

Substantiating the loss: what the tax authorities require, and for how long

The fact that the right to offset doesn’t lapse doesn’t mean the tax authorities have to simply take the figure at face value. The tax authorities retain the power to review the origin and amount of a carryforward loss generated many years earlier, even when those years already fall outside the general four-year statute of limitations for assessing the tax. That review power has its own, longer time limit, running from the end of the voluntary filing period for the year in which the loss was generated. Once that period has elapsed, the burden of proof shifts to the taxpayer: to keep applying the carryforward, the company must be able to substantiate it with the original tax return for the year the loss arose and the annual accounts filed with the Companies Registry for that year. Hence the practical importance of a simple habit: keeping all tax returns and accounting records for loss-making years carefully organized, company by company, even several years after the fact. Losing that supporting documentation is, in practice, the most common way of also losing the right to offset the loss.

Where carryforwards appear on Form 200

Form 200 includes a specific table, within the tax settlement section, detailing the offset of tax loss carryforwards: it breaks down, year of origin by year of origin, the amount generated, what has already been offset in prior years, and what is being applied in the current return, so that the balance still available for future years is tracked precisely. It’s essential that this table matches exactly what was declared in the years the losses originated: any mismatch between the carryforward balance on record and what was actually filed back then is one of the most common issues found when reviewing Form 200 returns inherited from prior advisors, and it often requires reconstructing several past years to properly substantiate the figure.

At Zythos Business we regularly come across companies carrying forward losses from years nobody has revisited since they arose, with supporting documentation scattered or incomplete. Part of our work with sole traders and SMEs is exactly that: reviewing the history, ensuring each carryforward loss is properly substantiated and tracked on Form 200, and applying the offset within the correct limits each year — so that loss, which already cost money when it happened, delivers its full tax value once the company is profitable again.