# Command-line interface#

You can use Tax-Calculator on your own computer via a command-line interface (CLI) called tc. This approach requires the use of a text editor to prepare simple files that are read by tc. Computer programming knowledge is not required, but this approach to using Tax-Calculator assumes you are willing to work at the command line (Terminal on Mac or Anaconda Prompt on Windows) and to use a text editor (for example, TextEdit on Mac or Notepad on Windows).

## Test tc CLI#

The tc CLI is part of the Tax-Calculator taxcalc package you installed on your computer as part of Getting started.

To check your installation of tc, enter the following command:

tc --test


Expected output (after a number of seconds) is PASSED TEST. If you get FAILED TEST, something went wrong in the installation process. If the installation test fails, please report your experience by creating a new issue.

If your installation passes the test, you are ready to begin using tc to analyze tax reforms. Continue reading this section for information about how to do that. But if you want a quick hint about the range of tc capabilities, enter the following:

tc --help


The basic idea of tc tax analysis is that each tax reform is specified in a text file using a simple method to describe the details of the reform. Read the next part of this section to see how policy reform files are formatted.

## Specify tax reform#

The details of a tax reform are contained in a text file that you write with a text editor. The reform is expressed by specifying which tax policy parameters are changed from their current-law values by the reform. The current-law values of each policy parameter are documented in this section of the guide. The timing and magnitude of these policy parameter changes are written in JSON, a simple and widely-used data-specification language.

For several examples of reform files and the general rules for writing JSON reform files, go to this page.

## Specify analysis assumptions#

This part explains how to specify economic assumption files used in static tax analysis. This is an advanced topic, so if you want to start out using the default assumptions (which are documented in this section of the guide), you can skip this part now and come back to read it whenever you want to change the default assumptions. The next part of this section discusses filing-unit input files.

The details of analysis assumptions are contained in a text file that you write with a text editor. The assumptions are expressed by specifying which parameters are changed from their default values. The timing and magnitude of these parameter changes are written in JSON, a simple and widely-used data-specification language.

For examples of assumption files and the general rules for writing JSON assumption files, go to this page.

## Specify filing units#

The taxcalc package containing tc does not include an IRS-SOI-PUF-derived microsimulation sample. This is because, unlike Census public-use files, the IRS-SOI Public Use File (PUF) is proprietary. If you or your organization has paid IRS to use the PUF version being by Tax-Calculator, then it may be possible for us to share with you our PUF-derived sample, which we call puf.csv even though it contains CPS records that represent non-filers. Otherwise, you have two choices.

First, you can easily create with a text editor a CSV-formatted file containing several filing units whose experience under your tax reform is of interest to you. Much of the public discussion of tax reforms is of this type: how is this family or that family affected by a reform; how do they fare under different reforms; etc. The test conducted to check the tc installation has left one such file. It is called test.csv and contains two filing units with only wage and salary income: a lower income family and a higher income family. You can use this test.csv file as tc input to analyze your tax reforms. Before creating your own input files be sure to read the short set of guidelines that appear after this list of two choices. Some people pursue this approach using a statistical pacakge like R or Stata, in which case the tc CLI program can be invoked from within the statistical package. There may be a need (especially on Windows) to add to the system PATH in order to do this.

Second, the taxcalc does include a freely available microsimulation sample containing only filing units derived from several recent March CPS surveys. For several reasons, the results generated by this cps.csv file are substantially different from the results generated by the puf.csv file. The cps.csv file contains a sample of the population while the puf.csv file contains mostly a sample of income tax filers in which high-income filing units are over represented. Also, the cps.csv file has many income variables that are missing (and assumed to be zero by Tax-Calculator), which causes an understating of total incomes, especially for those with high incomes. All these differences mean that the aggregate revenue and distributional results generated when using the cps.csv file as input to Tax-Calculator can be substantially different from the results generated when using the puf.csv file as input. And this is particularly true when analyzing reforms that change the tax treatment of high-income filers.

Input-File-Preparation Guidelines

The tc CLI to Tax-Calculator is flexible enough to read almost any kind of CSV-formatted input data on filing units as long as the variable names correspond to those expected by Tax-Calculator. The only required input variables are RECID (a unique filing-unit record identifier) and MARS (a positive-valued filing-status indicator). Other variables in the input file must have variable names that are listed in the Input Variables section for them to affect the tax calculations. Any variable listed in Input Variables that is not in an input file is automatically set to zero for every filing unit. Variables in the input file that are not listed in Input Variables are ignored by Tax-Calculator.

However, there are important data-preparation issues related to the fact that the payroll tax is a tax on individuals, not on income-tax filing units. Tax-Calculator expects that the filing-unit total for each of several earnings-related variables is split between the taxpayer and the spouse. It is the responsibility of anyone preparing data for Tax-Calculator input to do this earnings splitting. Here are the relationships between the filing-unit variable and the taxpayer (p) and spouse (s) variables expected by Tax-Calculator:

e00200 = e00200p + e00200s
e00900 = e00900p + e00900s
e02100 = e02100p + e02100s


Obviously, when MARS is not equal to 2 (married filing jointly), the values of the three s variables are zero and the value of each p variable is equal to the value of its corresponding filing-unit variable. Note that the input file can omit any one, or all, of these three sets variables. If the three variables in one of these sets are omitted, the required relationship will be satisfied because zero equals zero plus zero.

In addition to this earnings-splitting data-preparation issue, Tax-Calculator expects that the value of ordinary dividends (e00600) will be no less than the value of qualified dividends (e00650) for each filing unit. And it also expects that the value of total pension and annuity income (e01500) will be no less than the value of taxable pension and annuity income (e01700) for each filing unit. Tax-Calculator also expects the value of the required MARS variable to be in the range from one to five, and the value of the EIC variable to be in the range from zero to three. Again, it is your responsibility to prepare input data for Tax-Calculator in a way that ensures these relationships are true for each filing unit.

Here’s an example of how to specify a few stylized filing units with and without young children:

RECID,MARS,XTOT,EIC,n24,...
11   ,  1 ,  1 , 0 , 0 ,... <== single person with no kids
12   ,  4 ,  2 , 1 , 1 ,... <== single person with a young kid
13   ,  2 ,  4 , 2 , 2 ,... <== married couple with two young kids


Be sure to read the documentation of the MARS, XTOT, EIC, and n24 input variables. Also, there may be a need to add other child-age input variables if you want to simulate reforms like a child credit bonus for young children. Also, the universal basic income (UBI) reform is implemented using its own set of three age-group-count input variables.

The name of your input data file is also relevant to how tc will behave. If your file name ends with “puf.csv” or “cps.csv”, tc will automatically extrapolate your data from its base year to the year you specify for tax calculations to be calculated using built in growth factors, extrapolated weights, and other adjustment factors. If you are not using the “puf.csv” or “cps.csv” files produced by the TaxData project, it is likely that your data will not be compatible with these extrapolations and you should adopt filenames with alternative endings.

## Initiate reform analysis#

Executing tc requires only two command-line arguments: the name of an input file containing one or more filing units and the year for which the tax calculations are done. A baseline policy file is optional; specifying no baseline file implies the baseline policy is current-law policy. A policy reform file is optional; specifying no reform file implies calculations are done for the baseline policy. An economic assumption file is also optional; no assumption file implies you want to use the default values of the assumption parameters. The output files written by tc are built-up from the name of the input file, tax year, baseline file, reform file, and assumption file using a # character if an option is not specified.

Here we explain how to conduct tax analysis with tc by presenting a series of examples and explaining what output is produced in each example. There are several types of output that tc can generate so there will be more than a few examples. The examples are numbered in order to make it easier to refer to different examples. All the examples assume that the input file is test.csv, which was mentioned earlier in this guide.

tc test.csv 2020


This produces a minimal output file containing 2020 tax liabilities for each filing unit assuming the income amounts in the input file are amounts for 2020 and assuming current-law tax policy projected to 2020. The name of the CSV-formatted output file is test-20-#-#-#.csv. The first # symbol indicates we did not specify a baseline file and the second # symbol indicates we did not specify a policy reform file and the third # symbol indicates we did not specify an economic assumption file.
The variables included in the minimal output file include: RECID (of filing unit in the input file), YEAR (specified when executing tc), WEIGHT (which is same as s006), INCTAX (which is same as iitax), LSTAX (which is same as lumpsum_tax) and PAYTAX (which is same as payroll_tax).

Also, documentation of the reform is always written to a text file ending in -doc.text, which in this example would be named test-20-#-#-#-doc.text.

tc test.csv 2020 --dump


This produces a much more complete output file with the same name test-20-#-#-#.csv as the minimal output file produced in example (1). No other output is generated other than the test-20-#-#-#-doc.text file. The --dump option causes all the input variables (including the ones understood by Tax-Calculator but not included in test.csv, which are all zero) and all the output variables calculated by Tax-Calculator to be included in the output file. For a complete list of input variables, see the Input Variables section. For a complete list of output variables, see the Output Variables section. Since Tax-Calculator ignores variables in the input file that are not in the Input Variables section, the dump output file in example (2) can be used as an input file and it will produce exactly the same tax liabilities (apart from rounding errors of one or two cents) as in the original dump output.

This full dump output can be useful for debugging and is small when using just a few filing units as input. But when using large samples as input (for example, the cps.csv input file), the size of the dump output becomes quite large. There is a way to specify a partial dump that includes only variables of interest. To have tc do a partial dump, create a text file that lists the names of the variables to be included in the partial dump. You can put the varible names on separate lines and/or put several names on one line separated by spaces. Then point to that file using the --dvars option. So, for example, if your list of dump variables is in a file named mydumpvars, a partial dump file is created this way:

tc cps.csv 2020 --dump --dvars mydumpvars


If there is no --dvars option, the --dump option produces a full dump.

tc test.csv 2020 --sqldb


This produces the same dump output as example (2) except that the dump output is written not to a CSV-formatted file, but to the dump table in an SQLite3 database file, which is called test-20-#-#-#.db in this example. Because the --dump option is not used in example (3), minimal output will be written to the test-20-#-#-#.csv file. Note that use of the --dvars option causes the contents of the database file to be a partial dump.

Pros and cons of putting dump output in a CSV file or an SQLite3 database table: The CSV file is almost twice as large as the database, but it can be easily imported into a wide range of statistical packages. The main advantage of the SQLite3 database is that the Anaconda Python distribution includes sqlite3 (or sqlite3.exe on Windows), a command-line tool that can be used to tabulate dump output using structured query language (SQL). SQL is a language that you use to specify the tabulation you want and the SQL database figures out the procedure for generating your tabulation and then executes that procedure; there is no computer programming involved. We illustrate SQL tabulation of dump output in a subsequent section.

tc test.csv 2020 --dump --sqldb


This shows that you can get dump output in the two different formats from a single tc run.

The remaining examples use neither the --dump nor the --sqldb option, and thus, produce minimal output for the reform. But either or both of those options could be used in all the subsequent examples to generate more complete output for the reform.

tc test.csv 2021 --reform ref3.json


This produces 2021 output for the filing units in the test.csv file using the policy reform specified in the ref3.json file. The name of the output file in this example is test-21-#-ref3-#.csv because no baseline or assumption options were specified.

If, in addition to ref3.json, there was a ref4.json reform file and analysis of the compound reform (consisting of first implementing the ref3.json reform relative to current-law policy and then implementing the ref4.json reform relative to the ref3.json reform) is desired, both reform files can be mentioned in the --reform option as follows:

tc test.csv 2021 --reform ref3.json+ref4.json


The above command generates an output file named test-21-#-ref3+ref4-#.csv

tc test.csv 2021 --reform ref3.json --assump res1.json


This produces 2021 output for the filing units in the test.csv file using the policy reform specified in the ref3.json file and the economic assumptions specified in the eas1.json file. The output results produced by this analysis are written to the test-21-#-ref3-eas1.csv file.

In the preceding examples, all the output files are written in the directory where the tc command was executed. If you want the output files to be written in a different directory, use the --outdir option. So, for example, if you have created the myoutput directory as a subdirectory of the directory from where you are running tc, output files will be written there if you use the --outdir myoutput option.

The following examples illustrate output options that work only if each filing unit in the input file has a positive sampling weight (s006). So, we are going to use the cps.csv file in these examples along with the policy reform specified in the ref3.json file, the content of which is:

// ref3.json raises personal exemption amount to 8000 in 2022,
// after which it continues to be indexed to price inflation.
{
"II_em": {"2022": 8000}
}


The output options illustrated in the following examples generate tables of the post-reform level and the reform-induced change in tax liability by income deciles as well as graphs of marginal and average tax rates and percentage change in aftertax income by income percentiles. These tables and graphs are meant to provide a quick glance at the impact of a reform. Any serious analysis of a reform will involve generating custom tables and graphs using partial dump output. One of many examples of this sort of custom analysis is here.

$tc cps.csv 2022 --reform ref3.json --tables You loaded data for 2014. Tax-Calculator startup automatically extrapolated your data to 2022. ls cps-22* cps-22-#-ref3-#-doc.text cps-22-#-ref3-#.csv cps-22-#-ref3-#-tab.text$ cat cps-22-#-ref3-#-tab.text
Weighted Tax Reform Totals by Baseline Expanded-Income Decile
Returns    ExpInc    IncTax    PayTax     LSTax    AllTax
(#m)      ($b) ($b)      ($b) ($b)      ($b) 0 17.19 195.6 -6.1 20.9 0.0 14.8 1 17.19 500.1 -7.9 44.1 0.0 36.2 2 17.19 664.2 -2.7 51.7 0.0 49.0 3 17.19 829.5 1.3 68.5 0.0 69.8 4 17.19 1030.5 7.8 86.7 0.0 94.5 5 17.19 1273.3 16.7 103.9 0.0 120.6 6 17.19 1596.8 40.7 137.6 0.0 178.4 7 17.19 2044.5 81.4 183.3 0.0 264.7 8 17.19 2821.3 177.0 263.2 0.0 440.2 9 17.19 6369.3 1025.5 476.3 0.0 1501.8 A 171.93 17325.2 1333.8 1436.2 0.0 2770.0 Weighted Tax Differences by Baseline Expanded-Income Decile Returns ExpInc IncTax PayTax LSTax AllTax (#m) ($b)      ($b) ($b)      ($b) ($b)
0    17.19     195.6      -1.8       0.0       0.0      -1.8
1    17.19     500.1      -7.0       0.0       0.0      -7.0
2    17.19     664.2      -8.3       0.0       0.0      -8.3
3    17.19     829.5     -11.0       0.0       0.0     -11.0
4    17.19    1030.5     -15.1       0.0       0.0     -15.1
5    17.19    1273.3     -21.4       0.0       0.0     -21.4
6    17.19    1596.8     -28.9       0.0       0.0     -28.9
7    17.19    2044.5     -38.9       0.0       0.0     -38.9
8    17.19    2821.3     -62.9       0.0       0.0     -62.9
9    17.19    6369.3     -87.0       0.0       0.0     -87.0
A   171.93   17325.2    -282.4       0.0       0.0    -282.4


This produces 2022 output for the filing units in the cps.csv file using the policy reform specified in the ref3.json file. Notice that Tax-Calculator knows to extrapolate (or “age”) filing unit data in the cps.csv file to the specified tax year. It knows to do that because of the special input file name cps.csv. The tables produced by this analysis are written to the cps-22-#-ref3-#-tab.text file. Note that on Windows you would use dir instead of ls and type instead of cat.

Also note that the tables above in example (7) include in the bottom decile some filing units who have negative or zero expanded income in the baseline. If you want tables that somehow exclude those filing units, use the --dump option and tabulate your own tables.

$tc cps.csv 2024 --reform ref3.json --graphs You loaded data for 2014. Tax-Calculator startup automatically extrapolated your data to 2024.$ ls cps-24-*
cps-24-#-ref3-#-atr.html    cps-24-#-ref3-#-pch.html
cps-24-#-ref3-#-doc.text    cps-24-#-ref3-#.csv
cps-24-#-ref3-#-mtr.html


This example is like the previous one, except we ask for 2024 static output and for graphs instead of tables, although we could ask for both. The HTML files containing the graphs can be viewed in your browser.

Here is what the average tax rate graph in cps-24-#-ref3-#-atr.html looks like.

Here is what the marginal tax rate graph in cps-24-#-ref3-#-mtr.html looks like:

Here is what the percentage change in aftertax income graph in cps-24-#-ref3-#-pch.html looks like:

There is yet another tc output option that writes to the screen results from a normative welfare analysis of the specified policy reform. This --ceeu option produces experimental results that make sense only with input files that contain representative samples of the population such as the cps.csv file. The name of this option stands for certainty-equivalent expected utility. If you want to use this output option, you should read the commented Python source code for the ce_aftertax_expanded_income function in the taxcalc/utils.py file in the Tax-Calculator repository.

None of the above examples use the --baseline option, which means that baseline policy in those examples is current-law policy. The following example shows how to use the --baseline option to engage in counter-factual historical analysis. Suppose we want to analyze what would have happened if some alternative to TCJA had been enacted in late 2017. To do this we need to have pre-TCJA policy be the baseline policy and we need to have the alternative reform be implemented relative to pre-TCJA policy. The following tc run does exactly that using a local copy of the 2017_law.json file and the alt_reform.json file containing the alternative reform defined relative to pre-TCJA law.

$tc cps.csv 2019 --baseline 2017_law.json --reform 2017_law.json+alt_reform.json You loaded data for 2014. Tax-Calculator startup automatically extrapolated your data to 2019.  In all the examples in this section, we have executed one tc run at at time. But what if you want to execute many tc runs because you want results for many years and/or for several different reforms. Unless you are asking for full-dump output, a single tc run should take no more than one minute on your computer (even if you are using the large cps.csv input file). The easiest way to speed up the execution of many tc runs is to split them into groups of runs and execute each group of runs in a different command-prompt window. On most modern computers that have four CPU cores and a fast disk drive, executing four runs in different windows will take not much more time than executing a single tc run. If you have more than one run in each group, put them in a Unix/Mac bash script or a Windows batch file, and execute one script in each command-prompt window. If it still takes too long, consider splitting the tc runs across more than one computer. ## Tabulate reform results# Given that tc output can be written to either CSV-formatted files or SQLite3 database files, there is an enormous range of software tools that can be used to tabulate the output. You can use SAS or R, Stata or MATLAB, or even import output into a spreadsheet (but this would seem to be the least useful option). If you just want to compare the contents of two output files, you can use your favorite graphical diff program to view the two files side by side with highlighting of numbers that are different. The main point is to use a software tool that is available to you, that is appropriate for the task, and that you have experience using. Here we give some examples of using the sqlite3 command-line tool that is part of the Anaconda distribution (so it is always available when using Tax-Calculator). The first step, of course, is to use the --sqldb option when running tc. Then you can use the sqlite3 tool interactively or use it to execute SQL scripts you have saved in a text file. We’ll provide examples of both those approaches. There are many online tutorials on the SQL select command; if you want to learn more, search the Internet. First, we provide a simple example of using sqlite3 interactively. This approach is ideal for exploratory data analysis. Our example uses the cps.csv file as input, but you can do the following with the output from any input file that has weights (s006). Also, we specify no policy reform file, so the output is for current-law policy. What you cannot see from the following record of the analysis is that the sqlite3 tool keeps a command history, so pressing the up-arrow key will bring up the prior command for editing. This feature reduces substantially the amount of typing required to conduct exploratory data analysis. $ tc cps.csv 2016 --sqldb
You loaded data for 2014.
Tax-Calculator startup automatically extrapolated your data to 2016.

$sqlite3 cps-16-#-#-#.db SQLite version 3.22.0 2018-01-22 18:45:57 Enter ".help" for usage hints. sqlite> YOUR FIRST SQL COMMAND GOES HERE sqlite> YOUR SECOND SQL COMMAND GOES HERE sqlite> ... sqlite> YOUR FINAL SQL COMMAND GOES HERE sqlite> .quit  Second, we provide a simple example of using sqlite3 with SQL commands stored in a text file. This approach is useful if you want to tabulate many different output files in the same way. This second example assumes that the first example has already been done. Note that on Windows you should replace cat with type. $ cat tab.sql
-- tabulate unweighted and weighted number of filing units
select "unweighted count | weighted count (#m) of filing units";
select count(*),  -- unweighted count of filing units
round(sum(s006)*1e-6,3) -- weighted count of filing units (#m)
from dump;

-- weighted count by filing status (MARS)
select "filing status (MARS) | weighted count of filing units";
select MARS, -- filing status
round(sum(s006)*1e-6,3) -- weighted count of filing units (#m)
from dump
group by MARS;

-- tabulate weight of those with NEGATIVE marginal income tax rates
select "weighted count of those with NEGATIVE MTR";
select round(sum(s006)*1e-6,3) -- weighted count of filing units (#m)
from dump
where mtr_inctax < 0;

-- construct NON-NEGATIVE marginal income tax rate histogram with bin width 10
select "bin number | weighted count | mean NON-NEGATIVE MTR in bin";
select cast(round((mtr_inctax-5)/10) as int) as mtr_bin, -- histogram bin number
round(sum(s006)*1e-6,3), -- weight count of filing units in bin (#m)
-- weighted mean marginal income tax rate on taxpayer earnings in bin:
round(sum(mtr_inctax*s006)/sum(s006),2)
from dump
where mtr_inctax >= 0 -- include only those with NON-NEGATIVE marginal tax rate
group by mtr_bin
order by mtr_bin;

\$ cat tab.sql | sqlite3 cps-16-#-#-#.db
unweighted count | weighted count (#m) of filing units
456465|157.558
filing status (MARS) | weighted count of filing units
1|81.303
2|61.655
4|14.599
weighted count of those with NEGATIVE MTR
15.473
bin number | weighted count | mean NON-NEGATIVE MTR in bin
-1|26.896|0.0
0|2.606|7.18
1|60.85|14.11
2|37.803|25.54
3|12.804|32.26
4|1.0|43.08
5|0.11|55.74
6|0.015|66.76


The cat command writes the contents of the tab.sql file to stdout. We do nothing but that in the first command in order to show you the file contents. The second command pipes the contents of the tab.sql file into the sqlite3 tool, which executes the SQL statements and writes the tabulation results to stdout. (If you’re wondering about the validity of those high marginal tax rates, rest assured that all filing units with marginal income tax rates greater than sixty percent have been checked by hand and are valid: most are caught in the rapid phase-out of non-refundable education credits or in the phase-in of taxation of social security benefits. The negative marginal tax rates are caused by refundable credits, primarily the earned income tax credit.)

If you want to use the sqlite3 tool to tabulate the changes caused by a reform, use tc to generate two database dump files (one for current-law policy and the other for your reform) and then use the SQLite3 ATTACH command to make both database files available in your SQLite tabulation session.