Here’s a quick terminology lesson for non-accountants: your cost basis is what you paid for a property or other asset, including renovation costs.
Say you buy a property for $100,000, put $40,000 of repairs into it, then sell it for $200,000. You’d calculate your profit by subtracting your $140,000 cost basis from your $200,000 sales price, for a taxable profit of $60,000. (In the real world you’d have all kinds of other deductible expenses, such as the real estate agent’s commission, but they distract from the point at hand so we’re ignoring them.)
It’s easy enough to keep your receipts, invoices, and contracts when you’re flipping a house over the course of a few months. But what about when you own a rental property for 30 years? All those receipts, invoices, and contracts tend to get lost over the years, but they can help lower your capital gains tax bill when it comes time to sell.
The cost of every “capital improvement” you make to the property can add to your cost basis, reducing your taxable gains. Returning to the example above, you buy a rental property for $100,000, and over the next 30 years you pay $500 here and $1,500 there in capital improvements such as new windows, roof repairs, kitchen updates, landscaping, new driveways, and so forth. It adds up to $40,000 in total capital improvements, but it’s spread out over 30 years.
When you sell the property for $200,000, you can raise your cost basis by that $40,000 and pay capital gains on $60,000 rather than $100,000 — but only if you kept all those receipts and invoices. Save digital copies of all cost documents in a folder specifically for that property that you can pull up when it comes time to sell. It can save you tens of thousands of dollars in taxes!