how did the IRS or any other revenue agency audit dozens of millions of paper tax returns every year before computers were common?

Question

How did they verify if someone committed fraud or tax evasion in the 1950s for example?

In: 19

Answer 1

You send people to collect and verify records. Physically in person as well as phone calls, faxes and such.

You don’t verify *all* of the filings. You just look into the large or suspicious ones.