V-model with dynamic calue

I’m trying to autofill a calendar date based off a year from another calendar date. I can get the date to autofill but my data wont pass to my database when I try to save. Is there a way to input a value without changing v-model?

		fieldLabel="Expiration Date"
		v-model="workers_comp_liability_effective_date.replace('2020', '2021')"