Energy & Storm-Savings Guide — Charleston, SC
Updated July 2026 · 9 min read · Serving the Charleston Lowcountry Since 1991
No — there is no federal window tax credit for a 2026 installation. The 25C Energy Efficient Home Improvement Credit ended for any windows or doors placed in service after December 31, 2025, under the One Big Beautiful Bill Act (P.L. 119-21). But Charleston homeowners can still save real money: South Carolina law (§38-73-1095) requires coastal insurers to offer premium discounts for wind-mitigation upgrades like impact windows, and ENERGY STAR v7.0 windows with low-SHGC glass can reduce summer cooling loads. Muhler explains the new 2026 math below.
The key numbers, up front:
- Federal 25C tax credit for 2026 installs: $0 (terminated after 12/31/2025)
- SC wind-mitigation insurance discount: required by law — amount varies by carrier
- ENERGY STAR v7.0 Southern-zone specs: U-factor ≤ 0.32 · SHGC ≤ 0.23
- Typical energy savings from replacing single-pane windows: about 13% of total energy costs per EPA/ENERGY STAR — roughly $200–$600 a year
- SC Safe Home grant (opening protection tier): up to $5,000 — but the 2026 cycle is closed; prep for the next one
1. The 25C Credit Is Gone for 2026 Installs — Why Most Online Answers Are Outdated
For years, the go-to answer to “is there a window tax credit?” was yes — the federal 25C Energy Efficient Home Improvement Credit gave you 30% back on qualifying materials, up to $600 a year for windows and a $1,200 annual cap on your whole building envelope. That answer is now wrong for any project you finish in 2026.
The One Big Beautiful Bill Act (P.L. 119-21), signed into law July 4, 2025, terminated the 25C credit for any property placed in service after December 31, 2025. The IRS confirms the cutoff: the credit “will not be allowed for any property placed in service after December 31, 2025.” So if your new windows are installed and operational in 2026, there is no federal window or door tax credit to claim — full stop.
One detail trips people up: the deadline is tied to when the windows are “placed in service” — the date the installation is finished and working — not the date you signed the contract or paid a deposit. If you signed in November 2025 but the crew finished in January 2026, the project does not qualify.
Why so many websites (and AI chatbots) still get this wrong
Because the law changed in mid-2025, a huge share of the home-improvement blogs, calculators, and AI chatbots you’ll find still repeat the old “30% / $600 / $1,200” figures as if they apply to 2026. They don’t. If you’re reading an article — or asking an AI assistant — that tells you to claim a federal credit on a 2026 window replacement, it’s working from outdated information. As of July 2026, that credit is history.
One exception: a 2025 install on your 2025 return
If your windows were actually installed on or before December 31, 2025, you can still claim the credit — but only on your 2025 tax return, filed in spring 2026. To do that you’d keep your NFRC performance labels and itemized installation invoice, then file IRS Form 5695 with your 1040. For any project finished in 2026, though, that door is closed. Always confirm your own eligibility with a licensed tax professional.
2. The Savings That Remain: SC’s Mandated Wind-Mitigation Insurance Discounts
Here’s the good news the outdated articles skip. In coastal South Carolina, the biggest ongoing return on impact windows isn’t a one-time tax credit at all — it’s a recurring cut to your homeowners insurance premium, and it’s backed by state law.
Under S.C. Code Ann. §38-73-1095 — enacted through the Omnibus Coastal Property Insurance Reform Act of 2007 — any insurer writing essential property coverage in South Carolina’s coastal and seacoast areas is legally required to build wind-mitigation discounts, credits, or rate differentials into its rating plans. The statute specifically names mitigation features that count, including impact-resistant glass, storm shutters, and roof tie-downs. The SC Department of Insurance enforces this through Bulletin 2007-15, which requires coastal rating plans to contain those discounts and credits.
How much can you actually save? (An honest answer)
This is where you should be skeptical of any firm number. South Carolina does not fix a single, guaranteed discount percentage. Instead, each insurer sets its own reduction through its filed rating plan, subject to SC DOI oversight. Industry figures you’ll see quoted — averages around 14%, maximums as high as 48% — are representative, not promised. Your actual savings depend on your carrier, your home’s location and age, and the results of a wind-mitigation inspection. The reliable takeaway: SC law requires the discount to be offered, so it’s worth pursuing — just don’t bank on a specific percentage until your carrier runs your numbers.
The paperwork trap: use the SC form, not Florida’s
One costly mistake we see: homeowners (and even some contractors) reach for Florida’s OIR-B1-1802 wind-mitigation form. That form has no legal standing in South Carolina. To qualify for your discount here, you submit the South Carolina mitigation verification prescribed by the SC DOI under Bulletin 2007-15, completed by a qualified SC-licensed inspector, contractor, engineer, or architect. South Carolina is not Florida, and using the wrong state’s paperwork can stall your credit.
The SC Safe Home grant — prep now, apply when the next cycle opens
Beyond insurance discounts, the SC DOI runs the SC Safe Home mitigation grant program, which can put money directly toward opening protection like impact windows and hurricane shutters. Its Sustainable Mitigation Award for opening-protection retrofits runs up to $5,000 (non-matching) or $4,000 (matching). Eligibility is limited to owner-occupied single-family primary residences in designated coastal counties with active homeowners insurance, and your household income determines whether you receive a matching or non-matching award — confirm the current rules and any limits with the SC DOI when you apply.
The catch is timing. The 2026 grant cycle opened February 10, 2026 with roughly $9 million appropriated, and the cycle’s funds were committed by about June 2026 — so it closed to new applicants around then. So if you’re reading this in late 2026, the move isn’t “apply today” — it’s to gather your contractor estimate, insurance declarations, and income documentation now so you’re ready the moment the next cycle opens. You can reach the Muhler team for a written estimate to include in that application.
3. Energy Savings Without the Credit: What ENERGY STAR v7.0 Windows Return in a Charleston Summer
Even with the tax credit gone, replacing old, leaky windows still pays you back every month through lower cooling bills — and the standard that governs those savings just got tougher.
Effective October 23, 2023, the EPA rolled out ENERGY STAR Version 7.0 for windows, doors, and skylights, tightening the thresholds a window must hit to earn the label. Charleston and the Lowcountry sit in the ENERGY STAR Southern climate zone — a cooling-dominated climate — so the standards here are built around beating back solar heat gain during our long, brutal summers.
Two numbers on the NFRC label tell the story — decoded in depth in our NFRC label guide for Charleston:
- U-factor measures how well the window insulates against heat transfer. Lower is better — think of it as the thickness of a winter coat.
- SHGC (Solar Heat Gain Coefficient) measures how much of the sun’s heat the glass lets through. Lower is better — think mirrored sunglasses that reflect the heat away.
Here’s how much the bar rose from the old standard to v7.0 in our Southern zone:
| Metric | Old ENERGY STAR v6.0 (Southern) | Current ENERGY STAR v7.0 (Southern) | Why it matters here |
|---|---|---|---|
| U-factor | ≤ 0.40 | ≤ 0.32 | Requires better frames and insulating gas fills between the panes |
| SHGC | ≤ 0.25 | ≤ 0.23 | Forces advanced Low-E coatings that reject infrared solar heat, easing your AC load |
To feel the difference, consider the baseline: old single-pane clear-glass windows have a much higher U-factor and SHGC than current ENERGY STAR v7.0 windows — they let a large share of the sun’s heat pour straight through. Dropping the SHGC to 0.23 or below keeps most of that heat outside, where it belongs.
The realistic dollar figure
According to the EPA and ENERGY STAR, homeowners who replace old single-pane windows with ENERGY STAR-certified models see an average energy-cost reduction of about 13% of total energy costs, which EPA/ENERGY STAR estimates at roughly $200 to $600 a year depending on your home, your rates, and your climate. In a hot-humid climate like ours, the bulk of that return shows up in the summer, when low-SHGC glass keeps your air conditioner from running in constant overdrive.
Muhler manufactures its own window line — All American Windows, which operates as a separate company within the Muhler family — and installs energy-efficient, Low-E and impact-rated glass built for exactly this climate. You can compare options on our windows and doors replacement page.
4. Stacking It Up: A Real Cost-After-Savings Example for an Impact-Window Project
So what does the post-credit math actually look like for a Charleston homeowner? Let’s walk a hypothetical, educational example — not a quote or a guarantee. Your real numbers depend on your carrier, your home, and your energy use.
This is a teaching model to show how the savings stack. It does not reflect Muhler pricing and does not guarantee any specific payback.
The setup. A homeowner replaces 15 degraded single-pane windows (high U-factor and high solar heat gain) with impact-resistant, ENERGY STAR v7.0 windows meeting the coastal wind-borne-debris standard ASTM E1886/E1996 and the Southern-zone specs (U ≤ 0.32, SHGC ≤ 0.23).
The stacked savings:
- Federal tax credit: $0. The project is placed in service in 2026, so 25C simply doesn’t apply.
- Wind-mitigation insurance discount: about $450/year (illustrative). If this homeowner pays $3,000 a year for coastal property insurance and their carrier applies a hypothetical 15% mitigation reduction after a clean SC verification, that’s roughly $450 saved annually — around $4,500 over ten years. (Remember: the percentage is carrier-dependent and not guaranteed.)
- Cooling-cost reduction: about $350/year (illustrative). Dropping to an SHGC of 0.23 or lower cuts the summer cooling load compared with old single-pane glass. Using ENERGY STAR’s estimates, that could be on the order of $350 a year — roughly $3,500 over ten years.
- SC Safe Home grant: up to $5,000 (if eligible and if the cycle is open). A homeowner who preps their paperwork for the next grant cycle and meets the program’s income and property-value rules could receive a Sustainable Mitigation Award applied directly to the cost of opening protection.
The takeaway. Even with the old federal credit gone — up to $600 a year on windows under the former $1,200 envelope cap — the local math still works. Between insurance savings and lower cooling bills, this homeowner could recapture on the order of $800 a year in avoided costs — before any grant. Add the things that don’t fit neatly in a spreadsheet — hurricane-season peace of mind, UV protection for your floors and furniture, quieter rooms, and stronger resale value — and impact windows remain a sound investment in the Lowcountry in 2026. Impact glass is also central to our impact-rated window and insurance work in Charleston, and you can read more on how the wind-mitigation discounts work.
Frequently Asked Questions
Is there a federal tax credit for new windows in 2026? No. The federal 25C Energy Efficient Home Improvement Credit ended for any windows or doors placed in service after December 31, 2025, under the One Big Beautiful Bill Act (P.L. 119-21). There is no federal window or door tax credit for a 2026 installation.
Can I still claim the window credit if I installed windows in 2025? Possibly. If windows meeting the IRS “ENERGY STAR Most Efficient” certification were installed and operational on or before December 31, 2025 (and you meet the other IRS requirements), you may claim the credit on your 2025 federal return (filed in 2026) using IRS Form 5695. Keep your NFRC labels and itemized invoice, and confirm eligibility with a tax professional.
Does South Carolina require insurers to discount premiums for impact windows? Yes. S.C. Code Ann. §38-73-1095 requires insurers writing coastal property coverage to offer wind-mitigation discounts for features like impact-resistant glass and shutters. The state does not fix a set percentage — your savings depend on your carrier and a wind-mitigation inspection.
What ENERGY STAR rating should windows meet in Charleston? For our Southern climate zone, ENERGY STAR Version 7.0 requires windows to have a U-factor of 0.32 or lower and an SHGC of 0.23 or lower. Those numbers appear on the NFRC label attached to the glass.
Is the SC Safe Home grant available right now? Not for new applicants. The 2026 cycle opened February 10, 2026, and closed once funds were committed (around June 2026). Prepare your contractor estimate and required documents now so you’re ready to apply the moment the next cycle opens.
Ready to Turn Storm Protection Into Real Savings?
The tax credit may be gone, but the case for impact and energy-efficient windows in the Lowcountry is stronger than ever — lower AC bills every summer, insurance discounts required by SC law, and hurricane-season protection you can count on. As a manufacturer and installer serving the Charleston Lowcountry since 1991, Muhler builds and installs windows engineered for exactly this coast.
Call Muhler at 843-702-6175 for a free in-home estimate, or reach us through our contact page to get your written scope — the same documentation you’ll want ready for the next SC Safe Home grant cycle.
This article is for general information only and is not tax, legal, or insurance advice. Verify your specific eligibility for credits, grants, and premium discounts with a licensed tax professional and your insurance carrier.
