Billionaire Ken Griffin set a record with his $238 million condo — but New York City values the property only at $9.4 million.

The city’s property tax system requires all condos and co-ops to be assessed as if they were rental buildings, the Wall Street Journal reported. Assessors look at rental income at nearby buildings to estimate a condo’s value. So Griffin’s effective tax rate comes out to about 0.22 percent.

The tax rate is similar to that of other individual homes in Manhattan and prime Brooklyn neighborhoods where taxes have been capped as property values have climbed. The city undervalues condos in prime neighborhoods, according to the Independent Budget Office. Co-ops and condos were valued at about 20 percent of their market value, per estimates.

“It is a crazy system,” said Martha Stark, a former city finance commissioner. “The true market value bears no relation to sales price, and nowhere is that truer than among high-value coops and condos.”

In January, Griffin closed on a massive penthouse at 220 Central Park South. The priciest residential deal to date is a $361 million home in Hong Kong in 2017. While Griffin’s deal falls short of that purchase, it breaks the record for priciest U.S. home sold.

The tax rate on Griffin’s penthouse was determined before the purchase closed, and one expert told the Journal that the rate could increase come 2020. [WSJ] — Meenal Vamburkar