Never Claimed Depreciation on Your Rental? You're Probably Losing Twice

Plenty of people become landlords without deciding to. You move in with a partner, or take a job in another city, and rather than sell the old place you rent it out.

Nobody hands you a manual. So you declare the rent, you deduct the mortgage interest and the repairs, and you never touch depreciation — because nobody told you it existed.

If that's you, this is worth ten minutes. It's usually the single largest deduction on a rental, and there's a specific mechanism for claiming it late.

Why it matters twice over

The first loss is obvious: you've been paying tax on income you could have sheltered. Every year you didn't claim it, you overpaid.

The second one is the part that stings, and almost nobody sees it coming. When you eventually sell, the tax is calculated on the depreciation you were entitled to take — not the amount you actually claimed. It's often called the allowed or allowable rule.

So the deduction you never took still reduces what the property is treated as having cost you, and you're taxed accordingly. You skip the benefit and keep the bill.

The good news

You don't have to go back and amend six years of returns. In fact, for a missed method like this you generally can't.

Instead there's a catch-up: Form 3115, an application to change your accounting method. It lets you claim the whole cumulative amount as an adjustment in a single current year — often called a section 481(a) adjustment — rather than chasing it backwards year by year.

For someone who's been quietly not depreciating since 2019, that can be a substantial deduction landing in one return.

What your own number depends on

How much of the property is building rather than land. Land never depreciates, and the split is one of the things people most often get wrong.

What the property was worth when it became a rental. If it used to be your home, the starting figure isn't simply what you paid for it — converting a home to a rental has its own rule for setting that number.

How many years you've been renting it out. This one is just arithmetic, but it's what turns a modest annual figure into a meaningful catch-up.

Find out roughly what's sitting there

Our missed depreciation calculator takes the building value and the years you've been renting, and shows you the ballpark of what a catch-up could recover. Free, no sign-up, about two minutes.

Form 3115 itself is not a form to attempt casually — it's a method change, and the value at stake usually justifies having someone file it properly. If you'd like, you can ask to be introduced to a specialist in your state — no commitment or fee required.

Worth knowing: this is one of the more reliably worthwhile conversations a landlord can have, because the money is already sitting there — it just needs claiming.