A job change within my same company is prompting a FICA “reset.” How do I avoid overpaying FICA for 2020?

FICA taxes related to Medicare are charged on all income. So this will not affect that portion of the FICA taxes. However, in 2020, only $137,700 in wages are subject to Social Security taxes, which is the other part of the FICA tax.

In the event that you overpay, which is common when taxpayers switch employers, the overpayment will be added to your tax payments on Schedule 3, line 11, Excess social security. This amount is then included on your total payments reported on the Form 1040 and will be used to offset any tax due or included as part of your refund.

If it's truly just a different position with the same employer, the employer is required to limit the Social Security withholding to $8735.40 for 2020.  If they withhold too much, the employer must make the correction, return the amount of the excess withholding to you and correct your W-2.  Getting credit on your tax return for having excess Social Security withholding only applies when the over-withholding is the result of having different employers.