Building permits, zoning and land rules in Mills County, Texas

We could not confirm a general county building permit for a house in unincorporated Mills County, Texas. The county's published processes cover floodplain development, septic installation, county-road driveway access and subdivision platting, and the reviewed sources established no general residential building-permit process². Texas law limits county building-permit authority: fire-code permits for specified buildings are open only to counties with a population over 250,000 or adjacent to one, and residential-code standards need a commissioners court order¹⁰. No official record shows Mills County has adopted either program, so treat this as unconfirmed rather than assume state code inspections apply here.

Two exceptions matter. On a lot created by a subdivision outside a city, the final plat must be approved and recorded before construction begins⁴. In mapped flood hazard areas, a Floodplain Development Permit is required⁵. Industrialized housing and manufactured homes are a separate track regulated by the state rather than the county¹¹.

Mills County has no building or zoning department, so most land-use paperwork routes through one place: the County Judge's office at the Mills County Courthouse in Goldthwaite³. Septic (OSSF) permit applications, county-road driveway/access permit applications, and floodplain development permit applications are all submitted there^2,5,9. The County Judge also serves as Mills County's Floodplain Administrator, reviewing, approving or denying floodplain development permits⁵. For anything not covered here, call the County Judge's office first.

No. Texas grants county zoning power only to specific, legislatively named areas, and Mills County isn't one of them, so the county has no zoning ordinance and no zoning districts^1,6. Because the county has no zoning authority, it sets no minimum dwelling size, no minimum lot size, no setbacks, no lot-coverage limit and no building-height limit anywhere in unincorporated Mills County⁶. That's a legal consequence of state law, not a gap in local records: it applies countywide unless you're inside the City of Goldthwaite or another incorporated town, which can and do set their own rules.

An on-site sewage facility (septic) permit is required before you build, and Mills County itself is the local permitting authority, acting as TCEQ's authorized agent¹². Mills County's order requires a permit for all on-site sewage facilities in unincorporated areas regardless of acreage². Applications go to the County Judge's office with a nonrefundable $335 application/inspection fee, current as of September 1, 2025^2,3. Once installed, contact the county's on-site sewage inspector at least five working days before you want the inspection².

The state's 10-acre exemption exists, but Mills County's acreage-blind order means you should not rely on it without asking the County Judge's office first^2,8. An approved composting toilet still needs an approved OSSF for all other wastewater¹³. Soils are tight here: only about 5.9% of Mills County's land has soils without severe limits for a conventional drain field, so plan for an engineered or alternative system on most parcels¹⁴.

Yes, county rules don't restrict it: because Mills County has no zoning authority, there is no county rule limiting RV occupancy, tiny-home occupancy or manufactured-home placement on private land in unincorporated Mills County⁶. Accessory dwellings are likewise unrestricted by county rule⁶. That freedom is about zoning only; it doesn't remove your septic, driveway or floodplain-permit obligations, which apply regardless of what kind of dwelling you put on the land^2,5. If you're inside Goldthwaite or another incorporated city, that city's own rules take over instead.

1. Confirm the parcel is unincorporated, outside Goldthwaite or any other city with its own permitting rules¹.
2. Get a site evaluation for your OSSF (septic) early, since most of the county's soil isn't suited to a conventional drain field, and apply through the County Judge's office with the $335 fee^2,3.
3. If the lot was created by a subdivision, confirm its final plat was approved and recorded before you start construction⁴.
4. If your driveway will connect to a county road, submit a driveway/access permit and the $50 fee to the County Judge's office before starting work⁹.
5. If your parcel is in a mapped flood hazard area, get a Floodplain Development Permit from the County Judge's office before you build⁵.
6. Because we could not confirm a general county building permit, keep your septic permit, driveway permit and any floodplain paperwork on file in case a lender or insurer asks².

Soils and septic: under 6% of Mills County land is free of severe limitations for a conventional septic field, so budget for a site evaluation and possibly an engineered system before you commit to a parcel¹⁴. Terrain: almost 95% of the county sits at 15% slope or less, which is gentle building ground, though the land is mostly open rather than wooded¹⁴. Flood: a Floodplain Development Permit is required for construction in Mills County's mapped flood hazard areas, so check flood status with the County Judge's office before you buy⁵. Access: any new driveway onto a county road needs a $50 permit and 48-hour notice to the County Commissioner before work starts, and a driveway onto a state highway needs a separate TxDOT permit^9,15. Taxes: the effective property tax rate is about 0.9%, with a median annual bill near $1,762¹⁴.