Working from home one spouse using detailed method one using flat rate

[Craft03]

Me and my spouse both worked from home due to COVID. I’m using the flat rate and he’s using the detailed method. We rent an apartment. When calculating his expenses can I use the full amount of rent, hydro and internet? 

[KrisD15]

Yes, you needn't reduce those expenses because of the Home Office for which you are using the Simplified Method. 

The actual amounts will be reduced for the portion he claims as his office, so your office is irrelevant. 

[Craft03]

That’s great! Now I realize I calculated incorrectly last year is it too late to make the adjustments and refile?

[KrisD15]

If your tax would change, or your refund would increase for Tax Year 2021, you would need to file an amended Tax Year 2021 return. (1040X) 

You can do that in your TurboTax account. 

Here is a link about amending a prior year return in TurboTax.