Isle of Palms or Sullivan's Island? What Short-Term Rental Investors Need to Know Before Buying in Charleston in 2026

Jul 24

I get a version of the same phone call almost every week: an investor has found a charming beach house, they're picturing Airbnb income covering the mortgage, and then someone mentions "wait, can you even rent that short-term?" On Isle of Palms and Sullivan's Island — two barrier islands separated by about ten minutes of driving and a world of difference in rental policy — that question isn't rhetorical. It's the difference between a property that cash-flows and one that quietly turns into an expensive long-term rental you never planned on.

With mortgage rates still hovering in the mid-6% range and inventory finally loosening up across the Charleston region, I'm fielding more short-term rental inquiries than I have in the past two years. But the investors who do well aren't chasing the cutest listing photo — they're underwriting the regulatory environment first, the cash flow second. Here's how that math actually works right now, island by island.

Market Insight: Where Rates, Inventory, and Rental Demand Stand Today

Freddie Mac's Primary Mortgage Market Survey put the 30-year fixed rate at 6.58% as of July 23, 2026, up slightly from 6.55% the week before, with the 15-year fixed at 5.96%. That's not the sub-5% financing some buyers are still waiting on, and I'd stop waiting — rate relief has been incremental, not dramatic, for over a year now. For investment purchases, most of my clients are underwriting at 7%+ anyway once you factor in the investment-property rate add-on lenders charge over primary-residence pricing.

On the supply side, the Charleston Trident Association of Realtors' most recent regional data showed new listings up 4.4%, pending sales up 21.1%, and inventory up roughly 3% to 5,342 homes — a market that's loosening but still nowhere near a buyer's free-for-all, especially in the barrier island price bands.

The short-term rental data itself tells an interesting story. Charleston-area STR supply grew an estimated 44.6% over the past year, yet revenue and nightly rates both climbed anyway — a sign that traveler demand is still outpacing new listings, not the other way around. Depending on the data source, a well-run Charleston-area STR is generating somewhere between $58,000 and $75,000 in annual gross revenue, with occupancy running 65-74% for beachfront and near-beach product. Stabilized cap rates across the Charleston metro are running 4.5% to 6.5% — tighter than most secondary coastal markets, which tells you buyers are still paying a premium for Lowcountry scarcity.

Educational Value: How Isle of Palms and Sullivan's Island Rules Actually Differ

This is the part most out-of-town buyers get wrong, and it's not a minor technicality.

Isle of Palms — the investor-friendly island

Isle of Palms defines a short-term rental as anything rented for fewer than 30 consecutive days, and as of today there's no citywide cap on STR licenses. Residents actually voted down a proposed cap in a 2023 referendum by a 54% margin, which tells you the political appetite to restrict rentals isn't there. That said, "no cap" doesn't mean "no rules":

Every rental needs a current STR license, renewed annually.
Not every neighborhood qualifies — some HOA communities and residential-zoned pockets restrict or outright prohibit short-term rentals, so you have to check the parcel, not just the island.
Properties must meet life-safety standards: smoke detectors, fire extinguishers, marked egress, and parking ratios tied to bedroom count and occupancy limits.

Sullivan's Island — the restrictive neighbor

Ten minutes away, the rules flip almost entirely. Sullivan's Island enforces a 28-consecutive-night minimum stay, which functionally bans traditional nightly or weekly Airbnb-style rentals. The only exception is a small pool of grandfathered properties operating under a pre-2002 ordinance — and those licenses are non-transferable, meaning they don't automatically convey to a new owner at closing. That non-transferability is a resale-value issue as much as a rental-income issue, and it's one buyers routinely miss until it's too late.

[Internal link: Isle of Palms & Sullivan's Island new construction and insurance guide]

Buyer Strategy: How to Underwrite an STR Purchase Right Now

If I were putting my own capital into a Charleston-area STR this month, here's the checklist I'd run before writing an offer:

Confirm zoning and HOA status parcel-by-parcel on Isle of Palms. Don't rely on "the island allows it" — pull the specific address's zoning designation and any HOA covenants before you go hard on earnest money.
Model realistic occupancy, not peak-season occupancy. Use 65% as your base case, not the 74% best-case figure some listings advertise. Underwriting to the median, not the outlier, is what separates investors who sleep at night from ones who don't.
Budget for the 72-day tax trap. Once a property crosses roughly 72 days of rental activity in a year, it typically shifts from residential to commercial property tax classification — which can triple the tax bill. Build that into your pro forma from day one; don't get surprised by it at reassessment.
Layer in the full tax stack. South Carolina charges a 6% accommodations tax on secondary residences (4% on primary residences used as STRs), and Charleston-area local accommodations plus hospitality taxes can push the total tax burden on a booking above 10%. That's a direct hit to net yield — price it into your rate strategy, not as an afterthought.
Price off cap rate, not asking price. With stabilized Charleston STR cap rates running 4.5-6.5%, back into your maximum offer price from projected net operating income rather than anchoring to the seller's number.
Treat Sullivan's Island as a specialty play, not a default choice. Unless you're specifically targeting one of the rare grandfathered nightly-rental properties, underwrite Sullivan's Island as a long-term rental or personal-use purchase — not an STR play.

Local Market Context: The Bigger Picture Across Charleston

The barrier islands aren't the only piece of this story. Downtown Charleston has been tightening its own short-term rental permitting — the city stopped accepting new renewal applications for 2026 permits under its existing program, meaning the STR license itself has become a scarce, valuable asset on the peninsula in a way it isn't yet on Isle of Palms. If you're set on a peninsula STR, expect to pay a premium for a property that already carries a transferable, active permit.

For investors who want rental income without the STR regulatory maze entirely, Mount Pleasant, James Island, and Daniel Island remain strong long-term rental and appreciation plays, with steadier tenant demand tied to Charleston's ongoing job growth and Berkeley/Dorchester County population expansion feeding demand back toward the peninsula and islands. [Internal link: James Island investment property analysis]

On the construction side, new coastal builds on Isle of Palms and Sullivan's Island continue to carry the added cost of elevation requirements, wind-rated envelope systems, and flood-zone insurance premiums that inland Charleston product simply doesn't face. Those costs matter even if you're buying resale, because they set the replacement-cost floor under every property on the island — and they're a big part of why cap rates on the barrier islands run tighter than comparable coastal markets elsewhere in the Southeast.

Frequently Asked Questions

Can I short-term rent a house on Sullivan's Island?

Only if it's one of a limited number of properties grandfathered under a pre-2002 ordinance. Otherwise, Sullivan's Island enforces a 28-night minimum stay, which rules out traditional Airbnb-style rentals.

Is Isle of Palms a good Airbnb investment in 2026?

Generally yes — there's no citywide cap on STR licenses and residents voted against adding one in 2023. The catch is that not every neighborhood or HOA community on the island permits short-term rentals, so due diligence on the specific parcel is essential.

What's the accommodations tax on a Charleston-area vacation rental?

South Carolina charges a 6% state accommodations tax on short-term rentals used as secondary residences (4% for primary residences), and local Charleston-area accommodations and hospitality taxes can push the combined rate above 10% of the booking total.

Does renting my house short-term increase my property taxes?

It can. Once a property crosses roughly 72 days of rental activity per year, many Charleston-area jurisdictions reclassify it from residential to commercial for tax purposes — which can roughly triple the property tax bill. Model this before you buy, not after your first tax notice.

What cap rate should I expect on a Charleston short-term rental?

Stabilized STR properties in desirable Charleston-area locations are generally trading at 4.5% to 6.5% cap rates as of 2026 — tighter than many other Southeast coastal markets, reflecting continued scarcity of buildable and rentable barrier island inventory.

Can I still buy a short-term rental in downtown Charleston?

You can buy the property, but new STR permit applications for the city's 2026 program are not currently being accepted. Existing, transferable permits attached to a property carry real value — confirm permit status and transferability before you write an offer.

Ready to Buy, Build, or Invest in Charleston?

Looking to buy, build, or invest in Charleston real estate? I'm Chris Eller, Broker Associate with The Cassina Group and a luxury real estate developer specializing in new construction and coastal properties across Charleston and the barrier islands. Call/Text: 843-343-3359 | Email: Chris@TheCassinaGroup.com | Website: ChrisEllerRealEstate.com. If you're considering buying, selling, or building in Charleston or anywhere in the Lowcountry, reach out anytime for expert guidance.