Tax Authority Says Working From Home Can Cost You the Capital-Gains Exemption When You Sell Your Main Residence

If you work from home in Portugal, a recent position taken by the tax authority could quietly strip you of one of the most valuable breaks in the personal income-tax code: the exemption on capital gains when you sell your main home and reinvest the money in another one. In a binding ruling (informação vinculativa), the Autoridade Tributária e Aduaneira (Tax and Customs Authority, or AT) has concluded that if any part of a property is used for professional activity, the home no longer qualifies — and the gain becomes fully taxable.

The rule, and the catch

Under the personal income-tax code (Código do IRS), a gain on the sale of your own permanent residence is exempt from tax if you reinvest the proceeds in another permanent home in Portugal or the European Union within a set window. It is the mechanism that lets most families move house without handing a slice of the sale price to the state. The catch, according to the AT, sits in the word "exclusively": the law requires the property to be allocated to the taxpayer's own and permanent residence, and the authority reads that as meaning only to residence.

The ruling arose from the case of a retired lawyer who had practised from his home since 2019. When he came to sell, he had already changed the property's classification in the tax register from "services" back to "housing" in 2026. That was not enough. Because part of the dwelling had been assigned to his professional activity, the AT held that it had not been used exclusively as a permanent home, and refused the reinvestment exemption outright — regardless of the fact that he intended to reinvest in a new residence.

Tax advisers push back

Specialists have contested the interpretation, arguing that the AT is reading a condition into the law that the legislature never wrote. The statute exempts gains on a property used as a permanent home; it does not, they point out, say that a room used as a home office for part of the week destroys the benefit for the entire dwelling. There is no proportionality in the AT's reading — no test of how much of the floor area was professional, or for how long — only an all-or-nothing loss of the exemption. A binding ruling commits the authority to that stance until a court says otherwise, so taxpayers who disagree would have to litigate.

What this means for you

• Remote workers and freelancers: If you run a business or independent activity (recibos verdes) from your flat and have declared that address as your professional headquarters, you may be exposed when you sell.
• The home-office deduction trap: Claiming a share of rent, electricity or internet as a business expense is exactly the kind of "allocation to professional activity" the AT points to. A modest annual deduction could cost far more in tax on an eventual sale.
• Check the register before selling: As the lawyer's case shows, switching the property back to "housing" shortly before a sale did not save the exemption. Any advance planning needs to happen well before you list.
• Get it in writing: Anyone in doubt can request their own binding ruling from the AT, or take advice before signing the deed (escritura) — because once the gain is realised, the argument is far harder to win.

For now the AT's line stands, and it lands hardest on precisely the mobile, work-from-anywhere professionals who have made Portugal home in recent years. Until a tribunal tests it, the safest assumption is that mixing work and residence under one roof can carry a tax bill on the way out.