Currently, the U.S. federal government owns almost 50 percent of the land in the state. These include super-valuable real estate and facilities such as Camp Pendleton, Yosemite Park, the San Diego Naval Station, extensive national forests, etc., probably worth trillions of dollars at current value. So in exchange for gaining all this valuable property, the new country of California could agree to assume all current federal obligations for Social Security, Veterans benefits, Medicare, and other federal costs. Of course, since California opposes U.S. military policies, as a new country they would not need any military or military expenses.
California has the highest income taxes, sales taxes, and gas taxes in the country. Unconstrained by federal laws, they could really jack these up to European heights. All the European countries impose national sales taxes, sometimes called value-added taxes, of up to 24 percent at every level of sales: production, wholesale, and retail. In some European countries, income taxes start above 40 percent and go even higher. And with California’s apocalyptic environmental policies, they could increase gasoline taxes up to $5 more per gallon, ban all oil and gas production, and eliminate livestock production, because animals produce methane.
Just like some countries, the new country of California could eliminate paper and coin money. Sweden is currently banning all physical money, so every transaction must be digital. India has withdrawn most larger-denomination bills. The intention in these cases is to eliminate black markets, drug deals, and unreported income. California could have new monetary denominations worth $3, $15, and $30, because everything would be more expensive. If they had to issue physical money, I suggest the denominations depict Harvey Milk, Rodney King, and Caitlyn Jenner.