You can deduct the investment in a solar system on an existing building from your taxable income in the Canton of Zurich – for both cantonal/communal and federal tax. What's deductible is the cost after deducting any incentive contributions received. How much this brings depends on your marginal tax rate; for middle incomes the effect is often in the range of a fifth to a third of the investment. There is no deduction for new construction. Important for planning: with the abolition of the imputed rental value on 1 January 2029, the deduction for direct federal tax will lapse – it applies unchanged up to and including the 2028 tax period. (As of: September 2026, not tax advice)
Key points in brief
- Measures that save energy or use renewable energy count, for tax purposes, as deductible maintenance on existing buildings – the solar system is one of them.
- The deduction works twice: for direct federal tax and for Zurich cantonal and communal tax.
- Contributions received – above all the one-off feed-in incentive – reduce the deductible amount: it is the net cost that is deducted.
- For new construction, the system counts among the construction costs – no deduction. The distinction is trickier in individual cases than it sounds.
- If income in the investment year is not sufficient, the excess can be carried forward to the two following tax periods.
- Time window: deductible as today until the end of 2028; from 1 January 2029 the federal tax deduction lapses (abolition of the imputed rental value), while cantonally it may continue for a limited time depending on the canton – Zurich has not yet decided.
Why is a solar system deductible at all?
The principle comes from federal law: investments that serve energy saving and environmental protection are treated, for existing buildings, the same as maintenance costs – even though they actually increase the value of the house. This is a deliberate incentive by the legislator. The Canton of Zurich adopts this equal treatment for cantonal and communal tax, so the deduction applies at both levels.
In practice this means: the costs for modules, inverter, installation, scaffolding and electrical work go into your tax return as property maintenance – in the year you paid the invoices.
How large is the tax effect specifically?
This depends on your marginal tax rate – that is, on how heavily the last franc of your income is taxed. As a guide, deliberately given as an order of magnitude:
| Deductible net costs | Marginal tax rate ~20% | Marginal tax rate ~30% | Marginal tax rate ~40% |
|---|---|---|---|
| CHF 15,000.– | ~ CHF 3,000.– | ~ CHF 4,500.– | ~ CHF 6,000.– |
| CHF 20,000.– | ~ CHF 4,000.– | ~ CHF 6,000.– | ~ CHF 8,000.– |
| CHF 25,000.– | ~ CHF 5,000.– | ~ CHF 7,500.– | ~ CHF 10,000.– |
Simplified guideline values for illustration, as of: July 2026. The actual effect depends on income, municipality, denomination and family situation – the individual assessment is binding; when in doubt, it's worth consulting a tax professional.
For comparison: municipal solar incentives often amount to a few thousand francs. In the Canton of Zurich, the tax deduction is, for many households, the second-largest incentive channel after the one-off feed-in incentive – it just doesn't come as an incentive notice, but as a lower tax bill the following year.
What applies for new construction?
Here the answer is uncomfortable: no deduction. For new construction, the solar system counts among the building's construction costs – just like the roof or the heating. It only becomes tax-relevant again later, for example when the system is replaced or with a later extension on what is by then an existing building.
The grey area in between is tricky: if a system is retrofitted shortly after moving into a new building, the question arises of whether the building already counts as «existing» for tax purposes. Practice on this is shaped cantonally and has been clarified several times by court decisions in recent years – anyone in this situation is better off clarifying the individual case beforehand rather than hoping for a favourable assessment.
How are the one-off feed-in incentive and incentive contributions treated?
What's deductible is the net cost: investment minus contributions received. So anyone who invests CHF 28,000 and receives CHF 3,600 EIV plus a municipal contribution deducts the difference. Depending on whether the invoice and the incentive payment fall in the same tax year, the contribution is deducted directly or declared separately – what matters is that it appears. Silently deducting the gross amount regularly gets flagged at assessment, since incentive notifications are accessible to the authorities.
Ongoing income also has a tax side: remuneration for fed-in electricity generally counts as taxable income. How it is recorded in detail follows cantonal practice – check the current guidance sheet from the Zurich tax office or ask us for the documents for your system.
What if my income isn't enough in the investment year?
Since 2020: if the deductible investment costs exceed taxable income, the excess can be carried forward to the two following tax periods. This eases the situation for retiree households or families with a single income, where a large investment simply exceeds a single year's income.
There is also legal room for manoeuvre around the timing of payment: as a rule, the year of payment is decisive. Anyone who staggers instalment payments across the turn of the year spreads the deduction over two periods – whether that's worthwhile depends on your income situation and belongs in a short conversation with a tax professional before the payment schedule is fixed with the installer.
Until when does the deduction still apply? The abolition of the imputed rental value in 2029
The tax deduction has an expiry date – at least at the federal level. On 28 September 2025, the people and the cantons approved the system change in home-ownership taxation; the Federal Council set the entry into force on 1 April 2026 for 1 January 2029. From the 2029 tax period, the imputed rental value on owner-occupied residential property lapses – and with it the maintenance cost deduction, as well as, for direct federal tax, the deduction for energy-saving and environmental protection investments, which includes the solar system. Cantons may continue this deduction for a limited time (under the law, until 2050 at the latest); whether the Canton of Zurich will do so has not yet been decided. Nothing changes for rented properties.
What this means for your planning:
- Tax periods 2026 to 2028: the deduction applies unchanged for cantonal and federal tax – as a rule, the year of payment is decisive.
- From 2029: no more federal tax deduction for the solar system on an owner-occupied home; cantonally only if Zurich continues the deduction.
- Carrying forward the excess: whether an unused deduction from 2028 can be carried forward into the years after the system change depends on the transitional provisions – clarify with the tax office before staggering a payment beyond 2028.
- Unchanged: the one-off feed-in incentive, municipal and city contributions, and the electricity you save do not depend on tax law.
Sources: Federal Council/FTA, media release «Federal Council brings abolition of the imputed rental value into force as of 2029» (1 April 2026); popular vote of 28 September 2025. As of: September 2026, not tax advice.
How to enter the deduction in your tax return
1. Collect documents: final invoice(s), proof of payment, the EIV ruling from Pronovo, any municipal contributions. 2. Choose actual maintenance costs: in the investment year, you claim the actual costs instead of the maintenance flat rate – the flat rate would almost always be the worse choice for a solar investment. 3. Declare net costs: investment minus incentive contributions, with documentation. 4. Following years: declare feed-in remuneration according to the utility's statement; when carrying forward the excess, claim the remaining amount again.
In consultations, we regularly see prospective clients calculating over a few hundred francs' difference between two municipal programmes – while completely overlooking the tax deduction. Yet for middle and higher incomes in the Canton of Zurich, it is usually the bigger lever. Our advice: before signing the contract, have the full picture shown to you – system costs, EIV, any municipal contribution and a realistic range for the tax effect. Only that picture shows what the system really costs you net.
Note: this article does not replace tax advice; the individual assessment is binding.
Frequently asked questions
Can I also deduct a battery storage system?
If the battery is installed together with the system on an existing building, in practice it is regularly treated as part of the energy-saving investment. For a later, standalone installation, the classification is less consistent – clarify the case beforehand with the tax office or a professional.
Does the deduction also apply to condominium ownership?
Yes, pro rata: anyone participating via the community of owners in a system on the shared roof can generally claim their share of the costs on an existing building. The community's statement and cantonal practice are decisive.
Can I also deduct the maintenance flat rate in the same year?
No – per property and year, either the flat rate or the actual costs apply. In the year of the solar investment, you choose actual costs and also account for the rest of that year's maintenance there.
Do I have to pay tax on the one-off feed-in incentive as income?
The EIV is not «additionally taxed» but reduces the deductible investment costs – it still has to be declared, though. How the contribution and the deduction interact in time depends on the year of payment.
Does the solar system also reduce my wealth tax or imputed-rental-value taxation?
No, it brings no advantage there – the deduction works on income. The system flows into the property's valuation as part of the property; details are governed by cantonal assessment practice.
Does the tax deduction for the solar system still apply after 2028?
For direct federal tax, no: with the abolition of the imputed rental value as of 1 January 2029, the deduction for energy-saving investments on an owner-occupied home lapses. Cantons may continue it for a limited time – whether Zurich will do so is open. Up to and including the 2028 tax period, the deduction applies unchanged; rented properties are not affected.
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Sources: Cantonal Tax Office Zurich (guidance sheets on property maintenance), FTA, Pronovo AG; Federal Council/FTA, media release on the entry into force of the abolition of the imputed rental value (1 April 2026). As of September 2026.
Last updated: 9 July 2026 · Author: ecoEn editorial team
