Taxsim as a libary routine
Traditionally Taxsim has read its input from in ASCII from standard in
and written the results in ASCII to standard out. This has provided
portability and ease of diagnostics. But sometimes it may be inconvenient
or slow, so we are experimenting with a fast library interface. This
eliminates the ASCII to binary and back conversions. This page documents
how to use that version.
Note that the fortran code has no way to report errors other than to
abend, as fortran i/o is incompatible with c or Python i/o. If this
becomes a problem, we can perhaps address it with stop codes and global
variables. I am certainly willing to work with anyone wishing to use
Taxsim as a library routine - it isn't efficient to duplicate all the
error checking of income.
Source for the library is normally distributed as taxsimdll.f
The library source code differs from the executable
program in only 4 lines.
The source code contains several
references to "isexe" which needs to be set .false. in block data
dllexe. Three other changes need to be made to taxsim.f to get
taxsimdll.f:
<![CDATA[
sed -e "s/program taxsim/subroutine taxsim/" taxsim.f \
| sed "s/c return/ return/" \
| sed "s@isexe/.true./@isexe/.false./@" >taxsimdll.f
]]>
input and output are via Fortran common blocks. There is information
about accessing common blocks from Python is at:
<![CDATA[
https://numpy.org/doc/stable/f2py/python-usage.html#common-blocks
]]>
The input vector is common block "xcom" with 55 doublewords
(sorry it is numbered from 1):
1 taxsimid
2 year
3 state
4 mstat
5 page
6 sage
7 depx
8 dep13
9 dep17
10 dep18
11 pwages
12 swages
13 dividends
14 intrec
15 stcg
16 ltcg
17 otherprop
18 nonprop
19 pensions
20 gssi
21 ui
22 transfers
23 rentpaid
24 proptax
25 otheritem
26 childcare
27 mortgage
28 scorp
29 pbusinc
30 pprofinc
31 sbusinc
32 sprofinc
33 idtl
34 mtr
35 pui
36 sui
37 dep6
38 dep19
39 opt1
40 opt1v
41 opt2
42 opt2v
43 age1
44 age2
45 age3
46 age4
47 age5
48 age6
49 age7
50 age8
51 age9
52 age10
53 psemp
54 ssemp
55 statefip
The federal tax output goes to common block "newshr" with length 255 doublewords.
To start with, here are two important locations in newshr:
<![CDATA[
1 fiitax
74 siitax
]]>
For the rest of the federal results, consult the last few pages of
https://taxsim.nber.org/taxsim-ndx.txt where "comnew" is documented.
The state tax intermediate values are in common block "calc", with elements:
<![CDATA[
1 household income
2 rent paid
3 state agi
4 state personal exemptions
5 standard deduction
6 itemized deductions
7 taxable income
8 property tax cred
9 child care credit
10 earned income credit
11 total credits
12 bracket rate
13 tax before credits
14 rebate
15 fuel/energy credit
16 child tax credit
17 general credit
18 alternative minimum tax
19 deduction for federal taxf
20 rent credit
21 refundablecredits
22 primary taxable income
23 secondary taxable income
24 primary tax
25 secondary tax
]]>
If you want to use this code, please do not hesitate to contact me.
Daniel Feenberg
617-682-6204
feenberg@nber.org
last update 27 Sep 2024