There is an income-tax deduction that only exists for systems finished in 2026 and it is not the 40% or 60% energy-renovation relief. It is smaller, simpler and easier to miss on the calendar: 10% or 20% of what you pay this year, maximum base €5,000, and without the electrical installation certificate (CIE) there is nothing. Today is 27 August. Four months left, and legalising a plant is not a click.
If someone has mixed this box with the energy-performance-certificate ones, they have muddled you on purpose or by ignorance. Different rules. We cover 40/60 in 40% or 60%. This is the other one.
What the Official Gazette says, not the salesman
Royal Decree-law 7/2026 added the sixty-second additional provision of the Income Tax Act, with effect from 1 January 2026. Two modes, and you cannot claim both on the same installation:
- 10% of amounts paid between 1 January and 31 December 2026 to install renewable self-consumption — it may include storage — on a property you own.
- 20% if you own a dwelling in a predominantly residential building where that installation was carried out in 2026 (the homeowners-association / shared-roof case).
Maximum annual base: €5,000. That is not “they give you €5,000 back”. It is the cap on what enters the sum. 10% of 5,000 is €500. 20% of 5,000 is €1,000. If the system costs €12,000, the base is cut at 5,000.
The deduction is taken in the year the installation is finished, which cannot be later than 2026. You need the legal paperwork, in particular the CIE under the Low-Voltage Electrotechnical Regulations. Payment by transfer, card, nominative cheque or paying-in. Cash does not deduct. Grants received or awarded come off the base. If the system is used for a business activity, it does not apply; if you later put it to business use, you lose it.
How it differs from 40 and 60
| 2026 10% / 20% | Renovation 40% / 60% | |
|---|---|---|
| What the tax agency wants | A self-consumption system done, plus the CIE | An improvement on the energy performance certificate |
| Window | Payments and installation in 2026 | Works on different deadlines (building 60% until 2027) |
| Max base | €5,000/year | €7,500 (40%) or €15,000 accumulated (60%) |
| Battery | May form part of the system | Depends on whether it moves the certificate |
| What it is, really | A typical cap of €500 or €1,000 | Thousands, if you have income tax to pay |
They are not two names for the same thing. The 10% is a calendar nudge for whoever installs this year. 40/60 is a certificate file. A salesman who adds “10 + 40 + 60” on one slide is selling a sum the tax agency will not sign like that.
The clock, which is what hurts in August
To catch this box the installation must be finished in 2026, with its CIE. Signing is not enough. A deposit is not enough. The text talks about amounts paid in 2026 and an installation finished no later than 2026.
In practice, a study in September, a mount in October and a legalisation that snarls in November is roulette with €500 or €1,000. August still works. December, with holidays and industry appointments, does not.
€500 does not pay for a roof. Saying otherwise would be a lie. It is a real nudge for whoever was going to install anyway: a year of coffee, not a month. Losing it by signing on 20 December is ridiculous.
What we will not tell you
- That “the tax agency gifts you 10%”. It is a deduction on the tax due: if you have no income tax to pay, there is no magic.
- That it covers a 2025 system we legalise now. Read the year in the Gazette.
- That the 20% for buildings is automatic because you live in a flat. Title, who pays and what is installed on the common element all matter.
We are not tax advisers. Your gestoría has the last word on your return. We do what actually unlocks this box in real life: install, legalise and put the CIE in your hand inside 2026, not “when we can”.
If you are comparing quotes this week, ask for the CIE date, not the percentage on the slide. A percentage without a date is smoke.
→ Request your no-obligation study · WhatsApp 692 22 97 13 · 40% or 60%
Framework: 62nd additional provision of the Income Tax Act, inserted by Royal Decree-law 7/2026 of 20 March (Official Gazette 21/03/2026). General information as of 27/08/2026. It does not replace your tax adviser or an AEAT view of your case.