Each day, the U.S. government publishes an enormous amount of financial data, including its withholding-tax receipts. The report is titled The Daily Treasury Statement and is released every business day at 4pm (eastern time).
While the other tax data in the report is important, the withholding-tax is the real gem. The IRS is very strict about payroll taxes; companies are not allowed to delay payments. So, by watching the revenues as they come in, we have, by far, the best real-time indicator of the strength of the U.S. economy.
However, this data gets no respect from economists, and is still very obscure despite its incredible value. On this site, you can view numerous charts made from the data. If you subscribe, you will see the charts in real-time, updated every day. If you sign up for an institutional account, you will get a spreadsheet containing all the data going back to October 1, 1998. That’s thousands of data-points.
Note: The Social Security Administration (SSA) also publishes data, but it’s not quite the same thing. First, they don’t publish daily. Second, nobody pays taxes directly to the SSA. All taxes are collected by the Treasury Department, and then laws passed by Congress determine how much will be sent over to the SSA and Medicare. So, it’s a legislated number, rather than an observed number. And finally, the SSA doesn’t know anything about the income-tax portion of withheld taxes, which is a rather large component. So, the withholding-tax data presented on this site is really the only such data worth studying.