Here is guidance from the SC Dept of Revenue Sales Tax Manual. There is some additional commentary from MHISC in blue.
Calculation of the Tax: The maximum tax on the sale of a manufactured home, as defined in South Carolina Code §40-29-20, is calculated as follows:
(1)
subtract trade-in allowance from the sales price;
(2)
multiply the result from (1) by 65%;
(3)
if the result from (2) is no greater than $6,000, multiply by 5% for the amount
of tax due;
(4) if the result from (2) is greater than $6,000, the tax due is $300 plus 2% of the amount greater than $6,000.
Exemption for Tax in Excess of $300: A manufactured home is exempt from any tax in excess of $300 that may be due as a result of the calculation in item (4) above if it meets these energy efficiency levels: storm or double pane glass windows, insulated or storm doors, a minimum thermal resistance rating of the insulation only of R-11 for walls, R-19 for floors, and R-30 for ceilings.
However, variations in the energy efficiency levels for walls, floors, and ceilings are allowed and the exemption on tax due above $300 applies if the total heat loss does not exceed that calculated using the levels of R-11 for walls, R-19 for floors, and R-30 for ceilings.
Homes that qualify should have a sticker like this placed by the manufacturer, usually in the breaker box. That’s a really good tax rate, so I would only order new homes that qualify. If the home doesn’t have a sticker, we’d suggest contacting the manufacturer.
Records Requirements: The dealer selling the manufactured home must maintain records, on forms provided by the State Energy Office, on each manufactured home sold that meets the energy efficiency levels provided above. These records must be maintained for three years and must be made available for inspection upon request of the Department of Consumer Affairs or the State Energy Office.
Note: The maximum tax authorized does not apply to a single-family modular home regulated pursuant to Chapter 43, Title 23.
Furniture and Appliances Sold with the Home: Furniture and appliances are not considered a part of a manufactured or modular home, unless they are built-ins as noted below. For example, televisions, counter appliances, sofas, chairs and tables, even though sold with a home, are not a part of the home. Because these items are not a part of the home, they are taxed separately from the home at 6%, plus any applicable local sales and use tax, of their sales price less any trade-in allowed. The amount upon which the tax is calculated on furniture and appliances that are not built ins is the amount listed in the sales contract for these items or the retail fair market value of these items if the amounts for these items are not listed in the contract or if the amounts listed in the contract do not reasonably represent the retail fair market value of these items.27 Items such as disposals, built-in dishwashers, and built-in stoves are considered a part of the home and are not taxed separately from the home if installed at the time of the retail sale of the home.28
Heat Pumps, Air Conditioning Systems, Etc.: Heat pumps, air conditioning systems, skirting, steps, decks, septic tanks, wells, and driveways built or installed after the home is delivered to the construction site are not considered a part of the delivered home and are taxed separately from the home. The sale of these items to, or the purchase of these items by, the person who will build or supply and install them is subject to the tax at a rate of 6%, plus any applicable local sales and use tax.