I don’t know if this helps with the census table alignment but I can share the process I went through to get the IPUMS data on cost burden to approximate that found in the Harvard Joint Center on Housing Studies 2020 report on rental housing – using for both the 2018 ACS.
This table shows where I ended, with very close alignment of the two sets of numbers, this is for the entire U.S. rental population.
My first step was to run IPUMS for moderate and severe rent burden, below is the output table. To me these numbers were pretty close to JCHS on moderate rent burden and the entire population, but the severe rent burden population appears much further afield. (I originally had used the moderate range as .30 to .50 percent of income for rent, but found using the .4999 upper bound brought me slightly closer to JCHS on severe burden. Also, I’m using household income not family income as that is what it appears that JCHS uses.)
In the note to their data table, JCHS states that if a household has no income, they assume that the household is severely cost-burdened (JCHS table repeated at bottom of this email). So I did an additional run to just identify #s of households with 0 or negative income (column 1) and who paid some rent (row 2).
You can see that these households with 0 or negative income were for the most part excluded from the earlier IPUMS run on rent burden (total renters in 1st run 42,636,437, and total renters with some income, Col.2, in 2nd run 42,637,003). Therefore in the table at the top of this email comparing JCHS with IPUMs data I added 955,619 (renters with no income, paying some rent) to the severe rent burdened population figure in the first run (10,009,442), and used the total rental population figure from run 2 (43,725,353). These changes got me very close to the JCHS numbers.
As noted earlier, here is part of the JCHS table on rent burden showing the footnotes (Wyoming is the last row in that table and therefore shown, the total USA numbers can be found in row 1 of this table.)