ZIP 78666 (San Marcos, TX): income and new businesses
Updated 2026-10-15. Sources: IRS Statistics of Income ZIP code data and Texas Comptroller sales-tax permits.
In tax year 2022, residents of ZIP 78666 filed 36,290 federal returns covering about 59,940 people. Average adjusted gross income was $65,196 per return, about the same as the typical Texas ZIP ($69,978). That ranks #956 of 1,616 Texas ZIP codes.
From 2021 to 2022, average income per return rose 12.0% and the number of returns grew 2.3%.
18% of returns reported self-employment or small-business income (Schedule C), lower than the Texas rate of 24%. 16% claimed the Earned Income Tax Credit (state: 19%).
Since October 2025 the Texas Comptroller has issued 498 new sales-tax permits to business locations in 78666, about 13.7 per 1,000 returns, about the same as the Texas average of 13.0. That is up 60% on the 12 months before.
Income brackets in 78666
| Adjusted gross income | Returns | Share |
|---|---|---|
| $1 to $25k | 12,440 | 34% |
| $25k to $50k | 10,320 | 28% |
| $50k to $75k | 5,140 | 14% |
| $75k to $100k | 2,780 | 8% |
| $100k to $200k | 4,220 | 12% |
| $200k and up | 1,390 | 4% |
Tax return facts
| Measure | 78666 |
|---|---|
| Total adjusted gross income | $2,365,948,000 |
| Returns with wages | 30,860 (avg $50,724) |
| Returns with business income | 6,590 |
| Returns with dividends | 4,730 |
| Returns with retirement/pension income | 5,060 |
| Returns with unemployment pay | 630 |
| Earned Income Tax Credit claims | 5,750 ($13,816,000 total) |
New businesses by sector (since Oct 2025)
| Sector | New permits |
|---|---|
| Retail | 202 |
| Food & lodging | 72 |
| Manufacturing | 38 |
| Other services (repair, personal care) | 29 |
| Arts & recreation | 28 |
| Construction | 26 |
Most common new business types
| Business type (NAICS) | Code | New permits |
|---|---|---|
| Electronic Shopping and Mail-Order Houses | 454110 | 48 |
| Other Direct Selling Establishments | 454390 | 31 |
| Mobile Food Services | 722330 | 25 |
| Independent Artists, Writers, and Performers | 711510 | 20 |
| Snack and Nonalcoholic Beverage Bars | 722515 | 14 |
| Vending Machine Operators | 454210 | 13 |
| Full-Service Restaurants | 722511 | 13 |
| All Other Miscellaneous Store Retailers (except Tobacco Stores) | 453998 | 10 |
Monthly new permits
| Month | Permits | |
|---|---|---|
| Oct 2025 | 26 | |
| Nov 2025 | 17 | |
| Dec 2025 | 38 | |
| Jan 2026 | 31 | |
| Feb 2026 | 31 | |
| Mar 2026 | 37 | |
| Apr 2026 | 49 | |
| May 2026 | 51 | |
| Jun 2026 | 53 | |
| Jul 2026 | 53 | |
| Aug 2026 | 52 | |
| Sep 2026 | 46 |
How 78666 compares
| Measure | 78666 | Area (786xx, 15 ZIPs) | Texas |
|---|---|---|---|
| Avg income per return | $65,196 | $101,584 | $69,978 (typical ZIP) |
| New permits per 1,000 returns | 13.7 | 14.4 | 13.0 |
| Self-employment share | 18% | 20% | 24% |
Local business takeaways
- Arts & recreation makes up 7% of new permits here, 7.7x its share across these 300 ZIPs.
- Construction makes up 7% of new permits here, 2.2x its share across these 300 ZIPs.
- The busiest month for new permits was Jun 2026 with 53.
- 4% of returns report $200k or more, so price-sensitive offers usually fit better.
What this means
- Budgeting: the average return here works out to about $5,433 a month before tax. Try it in the 50/30/20 budget calculator.
- Selling to local businesses: 498 new locations opened in about a year, led by retail. The Texas new business list tool gives you the names and addresses, updated daily.
- Comparing areas: pull the same IRS numbers for any US ZIP with the ZIP income tool.
Nearby ZIP codes
| ZIP | Avg income per return | New permits |
|---|---|---|
| 78665 (Round Rock, TX) | $107,260 | 380 |
| 78664 (Round Rock, TX) | $79,234 | 411 |
| 78660 (Pflugerville, TX) | $87,252 | 707 |
| 78653 (Manor, TX) | $71,647 | 266 |
| 78681 (Round Rock, TX) | $131,950 | 314 |
| 78641 (Leander, TX) | $136,395 | 773 |
Notes on the data
IRS figures are for tax year 2022, the latest ZIP-level release, and count returns filed from addresses in the ZIP, not households. Adjusted gross income is income before the standard deduction. IRS rounds counts and leaves out very small groups. Permit counts include only locations still holding an active permit, so businesses that already closed are not counted. Permits cover businesses that sell taxable goods or services.
Get the full data
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Data from the IRS Statistics of Income program and the Texas Comptroller of Public Accounts. Figures are rounded by the source; check the original before relying on them. Not financial advice. Numbers are illustrative; your lender's statements control.