This publication is a rather detailed description of data from 1998 Utah state income tax returns. An income tax file is always dynamic, with late returns, amended returns, and audits changing the data. This means that in small ways the results depend on when the data to be analyzed is captured. This report analyzes 1998 return data as of March 15 of 2000.


State income tax returns include both full-year residents and non-residents, with the latter including those who moved in or out during the year, as well as those who never lived here but still have income from the state. We have presented broad summary data for non-residents, but for the most part have not presented detailed data, since its interpretation is difficult or meaningless, especially for statistical distributions.


This year’s report is mainly "statistical". The general strategy has been to report statistical points for the most important lines on the state form, with different tables according to the residency and filing status (Married, Single, etc), of the taxpayer. When not using an income breakdown, we have reported percentage deciles, as well as the mean, the median, and the mean for those claiming a non-zero amount. Since the number of returns is the same for each line, we have reported under the non-zero heading the number of returns not reporting zero for a given line. Table 5, rather than using an arbitrary income division which gets outdated over many years, uses income deciles relevant to the group being examined. ALower income" and Aupper income" show the income range.

A brief review of statistical terms for those not using them every day follows:

The mean is the total dollar amount divided by the number of returns.

The non-zero mean is the mean of non-zero data.

The median is the middle value.

A decile divides the values into tenths. For example the bottom decile reports the value dividing the bottom 10 percent from the top 90 percent, or the sixth decile divides the bottom 60 percent from the top 40 percent.

We think some of these issues will become clearer as we examine specific tables.


Summary table is an excerpt from table 2, and it shows, for all taxpayers, the total number using the line, the total amount claimed, and the average for all taxpayers and the average for those using the line.

The traditional table (page 4) reports for all full-year residents using traditional but arbitrary income brackets. It reports the number of returns, the amount of adjusted gross income, state income taxes, an effective tax rate and number of exemptions. The table labeled "calendar year" is for the 1998 returns only. We produce a similar table near the end of each year that includes the returns filed in that year for the previous two years, hoping that the late returns filed for the tax year two years ago represent the returns not yet filed for the one year ago return. For example, the data produced in late 1999 included 1998 and 1997 returns processed in 1999. We do this to parallel federal data.

Table 1 reports, for various residency and filing status groupings, the number of all returns filed and the deciles for adjusted gross income. It also reports the 5 percent and 95 percentage point breaks. These decile groupings are those used to define income groups on table 5.

Table 2 reports for each of the major lines, where data is available, various statistical measures for all taxpayers.

Table 3 is similar to table two, but there is a breakdown by residency. (Some lines may seem to be missing where there are narrower breakdowns, this is to prevent disclosure problems)

Table 4 is similar to table two, but it only includes full year residents and there is a filing status breakdown.

Table 5 reports by filing status for full-year-residents using an income breakdown based on adjusted gross income deciles. In addition to the income bracket limits and the number of non-zero entries, the total amount, the mean for all taxpayers in the group, the mean for non-zero entries, and the median are reported.


We are frequently asked about the number of taxpayers and the amount of Utah taxable income that is in each of the current state income tax brackets. The following two tables respond to that issue. For these tables we have collapsed the filing status groups into two, putting heads of households and married joint together, and amalgamating single filers with married filing single. We did this is because the tax brackets are the same for these groups.


Table 6 shows for each of the collapsed groups, the number of returns and the amount of taxable income in the lower brackets (all but the top) and the amount in the top bracket. It also reports the percent of returns and percent of taxable income in each bracket for each group. For example, 42.1 percent of all full-year returns are in the top bracket and file married joint or head of household; 66.9 percent of all full year taxable income is taxed at the top rate and belongs to the joint or household group. In summary, 65.0 percent of all taxpayers are in the top bracket and 82.0 percent of all taxable income is taxed at the top rate (up from last year).



Various tax credits and checkoffs are shown on table 8.