Tax records are one of my favorite sources to use when researching historic homes. Generally, I rely on them to help solidify a house’s construction date. Much of my work focuses on rural houses, where tax records are especially valuable in the absence of other sources, such as insurance maps or well-established newspapers. For any given property, they usually list the value of improvements separately from the value of the land. When tracked over a period of time, a significant increase in the value of improvements can indicate a major development such as the construction of a house.
The challenge is that historic tax records are often difficult to access—or may not be accessible to the public at all. In my experience, it varies state by state and county by county. In Indiana, the best tax records researchers have at their disposal are what are known as tax duplicates. Tax duplicates were the product of county auditors and county treasurers comparing and reconciling their tax records at the end of each year. Details found in tax duplicates include the legal description of a property, the owner, the assessed tax values, and taxes paid.
To illustrate my point on accessibility, lets look at two Indiana counties. Hendricks County astonishingly has all of its tax duplicates from 1841-1940 digitized and available online. Hamilton County, on the other hand, has nothing digitized, and its historic tax duplicates are not accessible to the public. In order to use them, you have to request a search to be done through the county treasurer’s office. If you're able to access tax duplicates yourself, they are relatively simple to search, even without an index. Duplicates are generally arranged by year, with records for each year organized by civil township and then alphabetically by the landowner’s last name.
Before consulting tax records, it’s helpful to have a defined year range to focus on so you don’t waste time collecting data from irrelevant years. Take my own house for example. It was built in the Italianate style, which suggests it was constructed between 1855 and 1890 (the peak of the style's popularity). I therefore would only gather values from the tax duplicates for the years 1855-1890 because it is unlikely my house was built outside of this time range. After reviewing the values for each year, the only significant increase occurs between 1880 and 1881, with a jump of $600 (remember: not market value, but nineteenth-century tax value, adjusted for the era). This jump in value in the records can be seen below:
It’s important to remember that a rise in improvement value is only indirect evidence of a house being built. Assessed tax values can reflect a variety of improvements, including barns, fences, or other structures. To confirm construction, it’s crucial to corroborate tax data with additional sources. In the case of my house, I know from deeds and land transfers that the Irwin family acquired the property in 1878. Furthermore, a claim against the estate of the previous owner details work done on a house that seems smaller than the one that stands today. These additional pieces of evidence, along with the jump in the improvement value between 1880 and 1881, suggest that my house was likely built or significantly expanded in 1880 after the Irwins purchased the property.
And, of course, sometimes you just get incredibly lucky in historical research. In my case, after concluding that the house was built in 1880 using tax records supported by land and probate records, I discovered a short newspaper announcement from May 1880 that confirmed my findings:
![A snippet from a historic newspaper with worn and faded text. It mentions "Mr. Irwin, of Brown [township], and Frank H...," describing their start of brick manufacturing to build new residences during the summer. The quality of the text makes some words difficult to decipher.](https://static.wixstatic.com/media/4e9a3d_1542ac0c0804459d90d46dd1c73d13ed~mv2.jpg/v1/fill/w_317,h_96,al_c,q_80,enc_auto/4e9a3d_1542ac0c0804459d90d46dd1c73d13ed~mv2.jpg)
The text is a bit difficult to decipher due to the physical state of the digitized page, but it reads, “Mr. Irwin, of Brown [township], and Frank Hufford, of this township [Lincoln], have begun the manufacture of brick, out of which they will erect new residences this summer.” A near-perfect corroboration of the tax record. Although they can often be underutilized, tax records are a great source for uncovering key facts about historic homes and properties. Using them to track improvement values and corroborating these findings with other historical sources can create compelling evidence. Whether you're a local historian, preservationist, or just a homeowner interested in the story of their house, tax records are a source worth looking at.