Estimated taxes

Estimated taxes are the unglamorous obligation that catches real estate investors off guard, because rental income, capital gains, and passthrough distributions arrive with no tax withheld. Unlike a paycheck, where an employer sends tax to the IRS for you, investment and business income requires you to pay the tax yourself, in four installments across the year. Miss the payments and you owe an underpayment penalty that is effectively interest on what you should have paid. The reassuring part is that a safe harbor lets you sidestep all the guesswork with one fixed number.

Who has to pay, and when

The rule is simple: if you expect to owe at least $1,000 in federal tax for the year after subtracting any withholding and refundable credits, the IRS expects you to pay as you go, in quarterly estimated payments. For a real estate investor with rental profit, capital gains from a sale, or passthrough income from an LLC, that threshold is easily crossed, so estimated payments are usually mandatory, not optional.

The 2026 payment deadlines fall on April 15, June 15, September 15, and the following January 15. Note that they are not evenly spaced (the “quarters” are uneven), so the schedule has to be watched. Miss a deadline or underpay, and the penalty under Section 6654 applies, calculated like interest on the shortfall from each due date, at a rate around 7% annualized for 2026. It is not a huge penalty on a small miss, but it compounds across four quarters and is entirely avoidable.

If you expect to owe $1,000 or more after withholding, you must pay estimated tax in four installments (April, June, September, and January), or face an interest-like underpayment penalty.

The safe harbor: one number, guaranteed protection

Here is the mechanism that removes the anxiety, and every real estate investor should use it. You are protected from the underpayment penalty, no matter how much you actually owe at year end, if your payments meet one of two safe harbors: 90% of the current year’s tax, or 100% of the prior year’s tax. The current-year option requires forecasting income you cannot yet know; the prior-year option is a fixed, known number, which makes it the planning default.

There is one wrinkle for higher earners: if your prior-year adjusted gross income exceeded $150,000, the prior-year safe harbor rises to 110% of last year’s tax. So the move is: take your total tax from last year’s return, multiply by 100% (or 110% if your prior-year AGI topped $150,000), divide by four, and pay that each quarter. Do that, and you cannot be penalized for underpayment even if you have a spectacular year, because you have met the safe harbor. This turns a moving target into a single fixed number you can pay on autopilot.

Paying 100% of last year’s tax (110% if prior-year AGI exceeded $150,000), split into four quarterly payments, protects you from any underpayment penalty regardless of what you actually owe this year.

Why the safe harbor matters most in a big year

The safe harbor’s real power shows up in exactly the years a real estate investor is most exposed: a year with a large capital gain from selling a property, or a big jump in rental income. In those years, your actual tax could be enormous, and trying to pay 90% of it in quarterly installments would require pre-paying a fortune before you even close the sale.

The prior-year safe harbor lets you avoid that. Because you only need to pay 100% or 110% of last year’s smaller tax to be penalty-safe, you can make your modest safe-harbor payments during the year and then settle the large remaining balance from the sale when you file, without any underpayment penalty on the difference. You still owe the full tax, but you defer paying the bulk of it until the filing deadline rather than pre-paying it quarterly, keeping the cash working in the meantime. This is a genuine, legal cash-flow advantage in a big gain year, and it is exactly why savvy investors lean on the prior-year safe harbor rather than the current-year method.

In a year with a large gain, the prior-year safe harbor lets you make small penalty-safe payments and settle the big balance at filing, deferring most of the tax without penalty.

The bottom line

• Real estate income has no withholding, so you must pay estimated tax quarterly if you will owe $1,000 or more.
• The 2026 deadlines are April 15, June 15, September 15, and January 15, and they are unevenly spaced.
• Underpaying triggers a Section 6654 penalty, effectively interest at around 7% for 2026, avoidable entirely.
• The safe harbor protects you if you pay 90% of this year’s tax or 100% of last year’s (110% if AGI over $150,000).
• The prior-year safe harbor lets you make small payments and settle a big gain-year balance at filing, penalty-free.

For the gains that drive a big-year bill, read capital gains tax on real estate. For surviving scrutiny of your return, see surviving an IRS audit. For the full picture, start at the advanced real estate tax strategies hub.

Last verified August 2026.