Lizzie Rovsek, a former cast member on "Real Housewives of Orange County," owes Uncle Sam a hefty chunk of change after allegedly not paying off her tax bill.

On June 21, Rovsek and her husband Christian were hit with a federal tax lien over unpaid back taxes.

The IRS claims the reality star has failed to pay up for the years 2013 and 2016. The breakdown for the taxes is $13,990 in 2013 and $20,527.30 in 2016 ... for a grand total of $34,517.85.

The "RHOC" star is still on the hook, along with her husband, for unpaid taxes from 2014 to the tune of $74,288.29 ... bringing the grand total up to a little more than $108k.

Lizzie was a main cast member on “Housewives” in season 9 and came back for season 10 as a friend of the cast. The reality star last appeared during season 12 as a guest.