CA State Taxes Situation with W-2c from Employer

[arj32754]

Hi,

I received W-2c for year 2020 and 2021 from my employer since I worked in Texas instead of California. Along with W-2c, I also received CA state tax and CA SDI for both these years from my employer in my bank account. However, while filing taxes before, I had already received state tax amounts from CA except the CA SDI. 
Now, It seems like I have received CA state tax from both CA tax refund and employer W-2c correction refund. I guess I need to file an amendment for this, so that I can refund back taxes to CA state. My questions are:

Are there any timelines or deadline to file amendments, whenever we receive W-2c from employer ? I wanted to know consequences, if we file late.

Thanks !

@MaryK4 

@ErnieS0 

[Bsch4477]

Generally, you must file Form 1040-X within 3 years after the date you filed your original return or within 2 years after the date you paid the tax, whichever is later.  This true for the IRS as well as California. 

Amended returns can take more than 6-9 months to process. 

[arj32754]

Will there be interest accured on the amount owed to California state. I am a bit confused because, I got state tax refunded while filing taxes for the year and now from the employer as well.