Every flip calculator, this one included, stops at profit before tax. On the example deal below that profit is $37,525, and which tax rule applies to it decides whether you keep about $29,269 or about $23,967.
The gap is bigger than most people expect, and it is not the gap between 15% and 20% that gets talked about on listing-site blogs.
What does the example flip make before tax?
A flip earns nothing until the house sells, so the profit is what is left of the sale price after every cost of getting there.
The flip calculator’s example buys at $150,000, puts $45,000 into the work and expects a finished value of $275,000. Buying costs are 2% of the price. A short-term loan covers 85% of the price and all of the work at 10% interest with 2 points, which is 2% of the loan paid up front. Carrying costs run $900 a month for six months, and selling costs are 8% of the sale price.
| One time | |
|---|---|
| Sale price | $275,000 |
| Purchase price | −$150,000 |
| Buying closing costs | −$3,000 |
| The work | −$45,000 |
| Carrying costs, six months | −$5,400 |
| Loan points and interest | −$12,075 |
| Selling costs | −$22,000 |
| Profit before tax | $37,525 |
These are example figures, not a forecast for any market.
That $37,525 took $42,975 of your own cash and six months. What the tax rules do to it comes next.
Why doesn’t the 15% capital gains rate apply?
Because the lower rate is for assets you held more than a year, and a flip is usually measured in months.
The IRS counts the holding period from the day after you acquire the property through the day you dispose of it. Hold it more than a year and the gain is long-term. A year or less and it is short-term, which is taxed at your ordinary income rates (Topic 409). The example flip sells at month six, so it is short-term before anything else is considered.
For gains that do qualify, the rates for tax years beginning in 2025 are 0%, 15% or 20%, with the 0% band running up to $48,350 of taxable income for a single filer and $96,700 for a married couple filing jointly, and 15% applying above that up to $533,400 single or $600,050 jointly (Topic 409). Those are the rates people have in mind when they budget 15% for a flip. Most flips never reach them.
When is flipping a business instead of an investment?
This is the rule that matters more than the calendar, because it can take capital gain treatment off the table however long you hold.
Capital gain rates apply to capital assets, and some property is specifically not a capital asset. Publication 544, the edition for 2025 returns, lists among noncapital assets “stock in trade, inventory, and other property you hold mainly for sale to customers in your trade or business” (Publication 544). A house bought to fix and resell can fall squarely in that description.
If it does, the profit is ordinary business income. Holding for thirteen months does not convert it into a long-term capital gain, and it cannot be rolled into a like-kind exchange the way an investment property can.
Whether your own flipping counts that way turns on the facts: how many houses, how often, how you found and marketed them, and how you treat the activity. One house fixed up over two years and a dozen a year are not the same case, and nothing here decides yours. That question belongs with a tax professional before your first sale, not after it.
What does self-employment tax add?
Once the profit is business income, a second tax lands on it that an investment sale never pays.
Self-employment tax is 15.3% in total, made up of 12.4% for Social Security and 2.9% for Medicare, and you generally owe it once net earnings from self-employment reach $400 (Topic 554). It is figured on about 92.35% of net earnings from the business. Social Security stops at an annual maximum, Medicare does not, and an additional Medicare tax applies above $200,000 of income for most filers and $250,000 for a married couple filing jointly.
On the example flip, 92.35% of $37,525 is $34,654, and 15.3% of that is $5,302.
What the three treatments leave on this flip
Here are the same $37,525 under each path, at an assumed 22% ordinary rate and the 15% long-term rate, before any state tax.
| Income tax | Self-employment tax | Left to you | |
|---|---|---|---|
| Long-term capital gain at 15%, held over a year | −$5,629 | – | $31,896 |
| Short-term capital gain at 22%, held six months | −$8,256 | – | $29,269 |
| Business profit at 22%, held mainly for sale | −$8,256 | −$5,302 | $23,967 |
The 22% rate is the example’s assumption, not a rule. Your own bracket, your state and the rest of your return move every figure in that table.
The top row is there for comparison, not as a plan. It is the treatment most flips cannot reach.
What this changes about the deal
It changes the margin you should be aiming at, because every flip yardstick in common use is a pre-tax one.
The example’s profit is 13.6% of the sale price. After the business-income path it is nearer 8.7%. A deal that looked like it had room for one bad surprise may not. How much profit should you make on a house flip and the 70% rule both work in pre-tax dollars, so treat their answers as the figure before this step, not after.
Holding longer to reach the one-year mark is not the escape it looks like either. Six more months of carrying costs on this deal is another $5,400 plus loan interest, and it does nothing at all if the house was held mainly for sale. Flipping or renting the same house compares the two paths on one property.
What to do before the first sale
Ask a tax professional which of the three rows above describes your plan, and ask before you buy, because the answer can depend on how the purchase is set up.
Then take whatever rate they give you and run the deal again with it, so the profit you are underwriting is the one that reaches your account.