In the US address system, the ZIP Code is not only a delivery identifier but also one of the most intuitive bases for determining which state an address belongs to. For overseas shoppers, forwarding services, cross-border e-commerce testing, and users who need to fill in US addresses, mastering the ZIP code rules of tax-free states can help you quickly verify whether an address truly falls within a tax-free state and avoid unexpected taxes caused by a mismatch between state and ZIP code. This article systematically introduces the ZIP code ranges, coding logic, and usage precautions for the 5 US tax-free states. If you need to directly generate real-format addresses for these tax-free states, you can use the US Tax-Free State Address Generator to obtain them quickly.

1. First, Understand the Coding Logic of US ZIP Codes

A US ZIP code consists of 5 digits and was introduced in 1963 by the United States Postal Service (USPS) to improve mail sorting efficiency. Its coding is not random but follows a geographic logic that goes from east to west and refines progressively[citation:13].

A 5-digit ZIP code can be broken down into three parts:

  • 1st digit: Represents a major geographic area of the US. 0 represents the East, with the number gradually increasing, and 9 represents the West[citation:13]. For example, New Hampshire ZIP codes start with 0, belonging to the East; Oregon starts with 9, belonging to the West.
  • 2nd–3rd digits: Represent a region or major city (Sectional Center Facility, SCF)[citation:3][citation:8].
  • 4th–5th digits: Identify the specific post office or delivery area[citation:3][citation:8].

In addition, USPS also provides the ZIP+4 format (such as 97201-1234), which appends 4 digits after the 5-digit ZIP code to further refine it to the block or building level[citation:3][citation:8]. However, when filling in a shopping address in daily life, a 5-digit ZIP code is sufficient.

2. Overview of Tax-Free State ZIP Code Ranges

The ZIP code ranges of the 5 US tax-free states are as follows. These ranges come from the official USPS and the US Financial Crimes Enforcement Network (FinCEN) ZIP code verification tables, with high stability, and the broad framework has remained basically unchanged for decades[citation:9][citation:4]:

  • Alaska (AK): ZIP code range 995–999[citation:9][citation:4]. The lowest ZIP code, 99501, is located in Anchorage, and the highest, 99950, is located in Ketchikan, which is also the highest ZIP code in the entire US[citation:13].
  • Delaware (DE): ZIP code range 197–199[citation:9][citation:4]. Commonly used ZIP codes include Wilmington 19801 and Dover 19901[citation:1].
  • Montana (MT): ZIP code range 590–599[citation:9][citation:4]. Billings 59101 and Helena 59601 are commonly used ZIP codes[citation:1].
  • New Hampshire (NH): ZIP code range 030–038[citation:9][citation:4]. Manchester 03101 and Concord 03301 are commonly used ZIP codes[citation:1]. Note that the ZIP code starts with 0, which cannot be omitted when filling in.
  • Oregon (OR): ZIP code range 970–979[citation:9][citation:4]. Portland 97201 and Salem 97301 are commonly used ZIP codes[citation:1].

As can be seen, the ZIP code ranges of tax-free states are continuous intervals, and the first three digits are enough to determine whether a ZIP code belongs to that state. For example, any 5-digit number starting with 97 falls within Oregon's range.

3. ZIP Code and State Must Match

This is the easiest pitfall to fall into when using tax-free state addresses: the state and ZIP code must match.

The vast majority of US states levy tax based on the "ship-to address"[citation:7]. If you fill in Oregon (OR) on a shopping website but enter California's 90001 as the ZIP code, the system may detect the address inconsistency when calculating tax, resulting in the inability to enjoy the tax exemption, or even triggering risk control[citation:2].

The rule for judgment is simple: check whether the first three digits of the ZIP code fall within the target state's range.

  • Oregon: ZIP code starts with 97, such as 97201 ✓
  • Delaware: ZIP code starts with 197–199, such as 19801 ✓
  • New Hampshire: ZIP code starts with 030–038, such as 03101 ✓
  • Montana: ZIP code starts with 590–599, such as 59101 ✓
  • Alaska: ZIP code starts with 995–999, such as 99501 ✓

Conversely, if the ZIP code is not within this range, even if the state is selected as a tax-free state, the address may still be judged invalid.

4. The Special Nature of Alaska ZIP Codes

Alaska is the most special of the 5 tax-free states. Although the state sales tax is 0%, local governments (cities, boroughs) have the authority to levy local sales tax, with rates usually between 0% and 7.5%[citation:1][citation:7].

This means that the same Alaska ZIP code may correspond to different tax rates in different cities. For example, some areas of Anchorage levy a local sales tax of about 3%[citation:16]. Therefore, if you use an Alaska address for forwarding or testing, it is recommended to prioritize areas that clearly do not levy local tax, or confirm the tax rate of the city corresponding to that ZIP code before filling it in.

In addition, Alaska's ZIP code range 995–999 spans a very large area, covering a vast region from Anchorage to remote areas. For forwarding scenarios, choosing the ZIP code of a major city (such as Anchorage 99501) is more reliable.

5. Do ZIP Codes Change?

This is a question many people care about. The answer has two layers:

  • State-level broad ranges are very stable: the first three-digit intervals of each state's ZIP codes have remained almost unchanged since the ZIP Code system was introduced in 1963. Ranges such as 97 for Oregon and 197–199 for Delaware can be used with confidence.
  • Specific ZIP codes are adjusted locally: USPS may add or adjust specific ZIP codes due to regional development, new post offices, and other reasons[citation:13]. For example, a rapidly developing suburb may be assigned a new ZIP code, but the new ZIP code will still be within the state's original broad interval.

Therefore, for state-level validation (checking whether the first three digits of a ZIP code belong to a tax-free state), the data is stable in the long term; if you need precision down to a specific street, it is recommended to use a near-real-time ZIP code lookup tool.

6. How to Quickly Check Which State a ZIP Code Belongs To

If you have a 5-digit ZIP code and want to confirm whether it belongs to a tax-free state, you can do this:

  • Check the first three digits: against the tax-free state ZIP code ranges above, those starting with 97x are Oregon, those starting with 197–199 are Delaware, those starting with 030–038 are New Hampshire, those starting with 590–599 are Montana, and those starting with 995–999 are Alaska.
  • Use the official USPS tool: USPS provides a Zip Code Lookup service. Enter the city and state to look up the corresponding ZIP code[citation:5].
  • Use an address generation tool: if you need to generate a tax-free state address, rather than look up an existing ZIP code, the US Tax-Free State Address Generator can directly generate a complete address with consistent state, city, and ZIP code logic, saving you the trouble of manual matching.

7. Frequently Asked Questions

Q: Do Oregon ZIP codes always start with 97?
A: Yes. Oregon's ZIP code range is 970–979, and all 5-digit ZIP codes starting with 97 belong to Oregon[citation:9].

Q: Why do New Hampshire ZIP codes start with 0?
A: The first digit of a US ZIP code increases from east to west, and 0 represents the eastern region. New Hampshire is located in the northeastern US, so its ZIP codes start with 0[citation:13]. The leading 0 cannot be omitted when filling in.

Q: Can Alaska ZIP codes enjoy complete tax exemption?
A: Not necessarily. Alaska has no state sales tax, but some cities levy local sales tax. Before use, it is recommended to confirm the tax rate of the city corresponding to that ZIP code[citation:1][citation:7].

Q: Where can I find the most accurate tax-free state ZIP code data?
A: For state-level ZIP code ranges, you can refer to the official USPS or FinCEN ZIP code verification tables[citation:9], and for the ZIP code of a specific address, you can use the USPS Zip Code Lookup[citation:5].

8. Conclusion

The ZIP code rules of US tax-free states are not complicated. The core is just three points: understand each state's ZIP code range, ensure the state and ZIP code match, and pay attention to Alaska's local tax exception. After mastering these rules, whether for overseas shopping forwarding, development testing, or filling in forms, you can quickly determine whether an address truly falls within a tax-free state.

If you want to directly obtain standard-format tax-free state addresses, the US Tax-Free State Address Generator provides one-click generation for the 5 states of Alaska, Delaware, Montana, New Hampshire, and Oregon, with consistent state, city, and ZIP code logic, and support for copy, favorites, and Excel export.