Home office deduction is calculated over the whole year or just from the start date of this home office use?

[ljmolina]

In turbotax guided home office deduction (web interface), it asked me about when this space started to be used as an office, for example from July 2020.  However this guide also asked me about the TOTAL rent expense of my whole house, and the TOTAL utilities expense of the whole house, insurance, etc.  I assumed it is asking me for the whole year (I read so!). Must I enter just those amounts from July till December or for the whole year (12 months)?  One expect that Turbotax will do the math, however It seems like turbotax is not computing just from July if I entered the 12 months expenses.

[Critter-3]

Enter the expenses for the time frame where you had the office ... later in the interview this info is presented : 

[ljmolina]

Thank you Critter.  So Turbotax Guided (step by step) is not doing the math.  Unfortunately it does not say "Enter the whole house expenses but just from the date you start your Home Office".  It says:  "Enter whole home expenses" giving the idea to enter the whole 12 months of the fiscal year.

I will only enter then from August to December. 

Thank you!