Employer has not withheld social security and Medicare taxes after visa status change from F1 to H1-B. How do I pay the taxes?

Hi!

 

My employer wasn't aware of my visa status change from F1 to H1-B and hence has not withheld any FICA taxes from my paycheck for the months of October, November and December 2020. Is there a way I can pay these taxes upfront while filing my returns ?