Bolthole Index

Hays County, Texas

Building permits, zoning and septic rules in San Marcos, Texas

Building inside San Marcos, Texas city limits requires a city building permit before any building or structure is placed, built or altered1. The city also applies its own Development Code for zoning2 and runs its own septic permitting program3. Land outside city limits in Hays County follows different rules4.

At a glance

Building permit
Required from the City of San Marcos for placing, building or altering a structure inside city limits1
Zoning
City Development Code applies inside city limits2
Septic permits
Issued by the City of San Marcos OSSF program inside city limits3
Building codes
2021 International Building Code and 2021 International Residential Code, with local amendments5
Initial permit review
5 working days6
Fee schedule
Published by the city; development fees updated effective October 1, 20267

Who to call

Building permits

City of San Marcos Permit Center

Building permits and inspections inside San Marcos city limits

512.805.2630

building_inspection_info@sanmarcostx.gov

630 East Hopkins, San Marcos, Texas 78666

Zoning

City of San Marcos Planning Department

Zoning, pre-development meetings and platting inside San Marcos

512.393.8230

planning_info@sanmarcostx.gov

630 East Hopkins, San Marcos, Texas 78666

Septic permits

City of San Marcos On-Site Sewage Facilities (OSSF) program

Septic system permits and inspections inside San Marcos city limits

512-393-8444

healthinfo@sanmarcostx.gov

Contact details are copied from each office’s official page and were checked against it on October 24, 2026.

Off-grid gear

Going off-grid in San Marcos means bringing your own water and power. The kit we’d start with:

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Do you need a building permit in San Marcos, Texas?

Yes. The City of San Marcos requires a building permit before any building or structure is placed, built or altered inside city limits1. Minor cosmetic work such as painting, carpeting, limited roof repair, siding installation or fixture replacement may be done without a permit1. San Marcos has adopted the 2021 International Building Code and 2021 International Residential Code, along with the 2020 National Electric Code, with local amendments5.

The city's initial review of a building permit application takes 5 working days, and total time varies with project complexity and submittal quality6. The permit checklist asks for a site plan, floor plan, framing details, foundation plan, electrical, plumbing and mechanical plans, and a copy of the recorded plat6. Inspections must pass before the city issues a certificate of occupancy8.

Who issues building permits in San Marcos, and how do you reach them?

Inside city limits, the City of San Marcos Permit Center handles building permits and inspections9. Call 512.805.2630 or email building_inspection_info@sanmarcostx.gov, at 630 East Hopkins, San Marcos, Texas 786669. The city publishes a fee schedule for building, engineering, planning, fire and neighborhood enhancement fees7.

Hays County Development Services does not issue building permits inside San Marcos. Its permits apply to unincorporated land, and the county notes that properties entirely within a municipality need no county platting approval10. See the Hays County page for rules outside city limits.

Does San Marcos have zoning, and what does it mean for RVs and tiny homes?

Yes. The San Marcos Development Code applies to land, structures, construction and uses inside San Marcos city limits2. Hays County, by contrast, lacks zoning authority outside the San Marcos Regional Airport zoning regulations, so county-level zoning does not fill the gap on unincorporated land4.

We could not confirm San Marcos's current district rules for minimum lot size, setbacks, lot coverage, building height, accessory dwellings, RV or tiny-home occupancy, or manufactured homes. Do not assume the relaxed rules of unincorporated Hays County carry over. Ask the City of San Marcos Planning Department at 512.393.8230 which district a lot sits in and what that district allows11.

How do septic permits work inside San Marcos?

The City of San Marcos runs its own on-site sewage facility (OSSF) program, which issues septic permits within city limits for commercial and residential properties312. Apply with a completed OSSF application through MyGovernmentOnline13. After plan review, the city issues an Authorization to Construct that expires one year from issue13.

No part of the system may be covered with ground until it passes an inspection with the city's designated representative14. The city charges a $415 fee for new installations and for repairs needing updated plans, and $250 for a re-inspection14. A permit to operate follows the passed inspections13. For questions call 512-393-8444 or email healthinfo@sanmarcostx.gov12.

Building a home in San Marcos: the steps, in order

  1. Ask the Planning Department which zoning district the lot is in and what it allows211.
  2. Apply for a building permit with a site plan, floor plan, foundation, framing and utility plans, and the recorded plat6.
  3. If the lot is not on city sewer, apply for an OSSF permit with the city's septic program13.
  4. Build to the adopted 2021 building and residential codes and local amendments5.
  5. Request the final inspections, which must be requested together and cover building, plumbing, mechanical, electrical and site8.
  6. Receive a certificate of occupancy once all inspections pass8.

What stays with Hays County, and what should you check before you buy in San Marcos?

Outside San Marcos city limits, Hays County's rules apply instead, and unincorporated septic permits come from the county rather than the city15. Hays County also states that development in its jurisdiction needs a county permit whether or not it is in a floodplain, and for property inside city limits the city's floodplain administrator may handle floodplain matters16. Confirm whether an address is inside city limits before choosing which office to call.

Hays County's effective property tax rate is 1.7%17, and the typical home value is $373,08718. A driveway onto a state highway needs a TxDOT permit on Form 105819.

Watch-outs

  • Owner-builder rules inside San Marcos city limits, private well permits, driveway permits and floodplain development rules are unconfirmed; ask the Permit Center at 512.805.26309.
  • The city's development fee schedule was updated effective October 1, 2026, so older fee quotes may be out of date7.
  • The city's septic program applies only inside city limits; for a lot outside them, the county issues septic permits15.

Sources

  1. Structures & Building Permits – Going Vertical (San Marcos), quoted and re-checked
  2. Codes & Ordinances | City of San Marcos, TX (San Marcos), quoted and re-checked
  3. On-Site Sewage Facilities | City of San Marcos, TX (San Marcos), quoted and re-checked
  4. Development & Planning, quoted and re-checked
  5. Codes & Ordinances | City of San Marcos, TX (San Marcos), quoted and re-checked
  6. Structures & Building Permits – Going Vertical (San Marcos), quoted and re-checked
  7. Development and Impact Fees | City of San Marcos, TX (San Marcos), quoted and re-checked
  8. Structures & Building Permits – Going Vertical (San Marcos), quoted and re-checked
  9. City of San Marcos Permit Center (sanmarcostx.gov)
  10. Development & Planning, quoted and re-checked
  11. City of San Marcos Planning Department (sanmarcostx.gov)
  12. City of San Marcos On-Site Sewage Facilities (OSSF) program (sanmarcostx.gov)
  13. On-Site Sewage Facilities | City of San Marcos, TX (San Marcos), quoted and re-checked
  14. On-Site Sewage Facilities | City of San Marcos, TX (San Marcos), quoted and re-checked
  15. Septic Permits, quoted and re-checked
  16. Floodplain, quoted and re-checked
  17. Effective property tax rate: Bolthole Index county data
  18. Typical home value (Zillow): Bolthole Index county data
  19. Section 4: Driveway Permits, Design, and Materials (Texas statewide rule), quoted and re-checked

Written October 24, 2026 from the rules quoted below, each taken from an official source and re-checked by an independent reviewer. This is research, not legal advice: rules change, so confirm with the office before you buy or build.

Answers from the rulebook for San Marcos

San Marcos’s own rules

  • Building permitRequired

    Placement, construction, or alteration of a building or structure inside San Marcos city limits.

    • Minor cosmetic work or repair such as painting, carpeting, limited roof repair, siding installation, or fixture replacement may be done without a permit.
    “A Building Permit is required prior to the placement, construction, or alteration of any building or structure within the City Limits.”
  • Building code adoptedAdopted (with conditions)

    Construction subject to San Marcos building permitting inside city limits.

    • The city's page states the listed codes were in effect as of April 1, 2023.
    • Local amendments adopted by Ordinance 2023-09 apply.

    International Building Code edition: 2021 · International Residential One/Two Family Code edition: 2021 · National Electric Code edition: 2020

    “The Building Code guides the Building Permit process of development. Download the Ordinance 2023-09 adopting these codes and local amendments. As of April 1, 2023, the following codes are in effect:”
  • InspectionsRequired

    Projects seeking a San Marcos certificate of occupancy inside city limits.

    • All building final inspections must be requested at the same time through MPN.
    • The listed finals include building, plumbing, mechanical, electrical, and site final inspections.
    “All inspections have been successfully passed”
  • Local zoningPresent (with conditions)

    Development, land, structures, construction, modifications, and uses inside San Marcos city limits.

    • The cited Development Code also applies in the ETJ; this claim is limited to city limits.
    “The San Marcos Development Code applies to [...] uses within the San Marcos City Limits”
  • Who permits septicLocal (with conditions)

    Commercial and residential septic systems inside San Marcos city limits.

    “provides permitting within the city limits for septic systems”
  • Septic permitRequired

    Commercial and residential on-site sewage facilities inside San Marcos city limits.

    • A completed OSSF application must be submitted.
    • An Authorization to Construct follows approved plan review and expires one year from issuance.
    • A permit to operate follows required passed inspections.

    Authorization to Construct validity: 1 year (from date of issue)

    “Once the plan review has been approved, you will be issued an Authorization to Construct (ATC) with an expiration date 1 year from date of issue.”
  • Septic inspectionRequired

    Construction of on-site sewage facilities inside San Marcos city limits.

    • No part of construction may be ground-covered before scheduling and passing a system inspection with the City designated representative.
    • An operational inspection may be scheduled at the inspector's discretion.
    • The permit to operate is issued upon passing required inspections.

    new-installation or updated-plan OSSF fee: 415 USD (repairs requiring updated plans) · re-inspection fee: 250 USD

    “Construction may begin at any point during the ATC time period, but you may not ground cover any part of the construction prior to scheduling and passing a system inspection with the City of San Marcos designated representative.”
  • Off-grid sanitationLimited

    On-site sewage facilities used for commercial or residential property inside San Marcos city limits.

    • The City OSSF program permits septic systems within city limits.
    • A system inspection must pass before any construction is ground-covered.
    • A permit to operate follows passing required inspections.
    “within the city limits for septic systems”
  • Permit feesPublished (with conditions)

    Development applications inside San Marcos city limits.

    • Resolution 2026-168R included Building, Engineering, Planning, Fire, and Neighborhood Enhancement fees.
    • The City page states the fee schedule became effective October 1, 2026.
    “charges fees for processing and review of development applications”
  • Permit processPublished (with conditions)

    Building permits for structures inside San Marcos city limits.

    • Initial application review is stated as five working days.
    • Permitting time varies by project complexity and submittal quality.
    • The permit checklist includes a building-permit application, plan-review fee, site plan, floor plan, framing details, foundation plan, electrical plan, plumbing plan, mechanical plan, and a copy of the recorded plat.

    initial review: 5 working days

    “Initial review of application: 5 working days”

Still unanswered

We looked and could not find an official answer yet. Silence is not permission; ask San Marcos or Hays County directly.

  • Owner-builder exemption — Owner-built residential construction inside San Marcos city limits.
  • Zoning districts — Zoning districts inside San Marcos city limits.
  • Minimum dwelling size — Residential districts inside San Marcos city limits.
  • Minimum lot size — Residential districts inside San Marcos city limits.
  • Setbacks — Principal residential structures inside San Marcos city limits.
13 more unanswered
  • Lot coverage
  • Building height
  • Living in an RV
  • Camping on your land
  • Tiny homes
  • Manufactured homes
  • Accessory dwellings
  • Well permit
  • Mandatory utility hookup
  • Agricultural exemption
  • Subdividing land
  • Driveway access
  • Building in a floodplain

Each answer was extracted from an official source and independently re-checked against that source by a second reviewer. That is an evidence check, not legal advice. Rules change; confirm with the authority before you buy or build.

Unanswered questions are usually a sign that San Marcos publishes no rule on the point, not that none exists. Hays County’s page lists the county offices to call.

← All of Hays County: county rules, score and offices