Rent or sell after a renovation? Run both numbers

One refurbished property, two exits. What selling and refinancing each measure, why a single figure cannot compare them, and what tips the balance.

Updated on 8 August 2026

Short answer

A renovated property gives two different answers, and neither is a single return figure. Selling turns the whole project into one payment now, and triggers a capital gains tax event. Refinancing onto a buy-to-let mortgage returns most of the same cash, keeps the asset, and leaves the gain untaxed until you sell.

Sell = £27,443 after assumed tax, once Refinance and let = £61,350 released, plus £2,003 a year

On the terrace below, the sale annualises to 40.1% on the cash employed. The refinance route returns 4.2% a year on the cash left behind it.

What the two routes actually measure

Selling and letting answer different questions, so they produce different units. A sale measures profit over a project with a start and an end. Letting measures income over a holding period with no fixed end.

That difference is not cosmetic. A sale return is a percentage of the cash you employed, earned once. A letting return is a percentage of the cash you left in, earned again every year. Setting a one-off 40.1% against a yearly 4.2% means nothing without a time axis under both.

The UK adds a second difference on top. A sale is a disposal, so capital gains tax falls due. A remortgage is not a disposal, so it does not.

Capital drawn out of the property therefore reaches your account without a tax event. The gain itself stays intact, and stays chargeable for the day you sell.

Most investors run only one of the two calculations. That is understandable. The project was set up as a flip, or set up as a hold, and the other route never gets a model.

A free rental property spreadsheet will handle the letting side of the question. It will not touch the sale side, and that is the half most flips never model.

The project: a £176,000 terrace with £54,500 of works

The project below is a three-bed terrace bought at £176,000, refurbished over eight months, and valued at £295,000 on completion. Purchase costs came to £12,300, most of it stamp duty land tax with the additional dwelling surcharge. A bridging loan of £142,000 ran at 8.4% throughout.

Cash employed = £250,752 - £142,000 = £108,752

In England and Northern Ireland the additional dwelling SDLT surcharge is 5% on top of the standard residential rates, for transactions on or after 31 October 2024 (HMRC). Scotland charges ADS and Wales charges higher rates of LTT, on their own thresholds.

That surcharge is already spent on this project. It still returns to the decision, because selling and buying again pays it a second time.

Route one: sell at £295,000

Selling at £295,000 does not put £295,000 in the bank. Estate agency at 1.2% plus VAT costs £4,248. Conveyancing, the EPC and disbursements add £1,380 on top.

The taxable gain is not that profit. Allowable expenditure for capital gains tax covers acquisition, disposal and enhancement costs. Finance costs are not enhancement, so the £7,952 of bridging interest cuts your cash profit while leaving the gain where it is.

For 2025/26, HMRC charged individuals 18% and 24% on residential property gains, depending on the income tax band the gain falls in. The annual exempt amount was £3,000 that year, and the table above ignores it.

Rates and allowances move at every Budget, so check the year you actually sell in. UK residential gains must also be reported and paid within 60 days of completion (HMRC, rule in force since 27 October 2021).

Return on cash employed = £27,443 / £108,752 = 25.2% over eight months Annualised = (1 + 0.252) ^ (12 / 8) - 1 = 40.1%

Route two: refinance at 70% and let

Refinancing swaps the bridging loan for a buy-to-let mortgage against the new valuation. The obvious move is 75% of £295,000. The lender's interest coverage test blocks it.

At a rent of £1,475 a month and a stress rate of 6.75%, a 75% loan of £221,250 gives an ICR of 119%. That fails a 125% floor. A 70% loan of £206,500 clears it with room.

ICR at 70% LTV = £1,475 / £1,162 = 1.27, or 127%

So the stress test, not the headline LTV cap, decides how much cash comes back. The same test on a standing rental is worked through in the buy-to-let stress test.

Cash on cash = £2,003 / £47,402 = 4.2% a year

Tax lands differently on this route. An individual landlord is taxed on rental profit before finance costs, so on £12,927 rather than on the £2,003 of cash flow. A 20% basic rate reducer then applies against the £10,924 of interest.

That rule is section 24, phased in from 2017 and complete from April 2020 (HMRC, restricting finance cost relief for individual landlords). A higher-rate taxpayer keeps distinctly less of the same £2,003.

Which route the numbers favour

The sale wins on speed and on the size of the headline number. It also ends the project. The refinance hands back £61,350 of the £108,752 employed, leaves £47,402 working, and keeps a £295,000 asset with a mortgage against it.

Neither percentage is risk adjusted. The 40.1% assumes a buyer pays £295,000 inside eight months. The 4.2% assumes a tenant pays £1,475 a month for years, and that the rate at the next remortgage behaves.

What tips the balance in the UK

These are practical considerations, not a calculation rule.

The last row carries more weight than it looks. Buying, refurbishing and selling as a pattern can be treated as a trade rather than an investment. Income tax and National Insurance then apply in place of capital gains tax, and the badges of trade decide which it is (HMRC). One project rarely settles that question. Five in a row can.

Lender timing rules bite too. Many UK lenders apply a six month ownership rule before they will lend against a new valuation, though not all do. Treat that as an indication, not a benchmark, and confirm it with the lender before you build an exit around it.

Two mistakes in this comparison

Comparing 40.1% with 4.2% as if they share a unit is the first mistake. One is a whole project annualised from eight months. The other repeats every year for as long as you hold the property. Put both on a timeline before you rank them.

Assuming one value serves both routes is the second. The £295,000 here is an agent's view of what an owner-occupier will pay. A remortgage valuation is a lender's surveyor working to a different brief, and it often lands lower. Model the refinance at a figure that would not surprise you, then check whether 70% still releases £61,350.

Frequently asked questions

Does refinancing after a renovation trigger capital gains tax?

No. A remortgage is not a disposal, so no chargeable gain arises when you draw capital out. The gain stays attached to the property and becomes chargeable when you sell. Releasing £61,350 through a buy-to-let mortgage therefore reaches your account untaxed, and the eventual bill is unchanged.

Can I compare the sale return with the rental return directly?

Not as they stand. The sale figure of 25.2% covers eight months, and annualising it produces 40.1%. The rental figure of 4.2% repeats each year on the cash left in the property. Compare an annualised project return with a yearly cash-on-cash return, and never the two raw percentages.

What if the remortgage valuation comes in below £295,000?

The release shrinks with it. At a £280,000 valuation, 70% is £196,000, so the cash out falls by £10,500 before any change in rent. Interest cover improves slightly, because the loan is smaller. Run the letting route twice, at the agent's figure and at a valuation ten per cent lower.

Does HMRC treat a refurbish and sell project as trading?

It can. Where the intention at purchase was resale at a profit, HMRC may treat the activity as a trade, taxed as income rather than as a capital gain. The badges of trade are the test, and the frequency of transactions is one of them. Have that judged on your own facts.

Run your own numbers

Enter the purchase price, works budget and bridging interest once, read the sale return, then enter the same property as a rental with the refinanced loan. The transformation calculator covers the first route.

BRIX Calc runs one project free, and PRO removes the project limit. The rental calculator takes rent, voids, running costs and the new mortgage, and returns NOI, cash flow and cash on cash. It does the arithmetic on your inputs. It does not give tax advice and it does not fetch market data.