You have a current home office and you deducted Year 1 in 2018, but in 2019, you added square footage.
In your case, this changes the percentages of what you can deduct and depreciate on the SCH C. There are several ways to do this. The simplest way is to close the old home office. Then open a new home office with the new, larger square footage. Take note that the dates can not overlap. For example, the closing date of the old home office "MUST" be at least one day before the opening date of the new home office.
You will need to keep a record of all depreciation taken on the old home office, and keep that record forever. You will be required to recapture that depreciation when you sell or otherwise dispose of the property in the future.
Finally, assuming this is a SCH C business we're discussing here, depreciation is over 39 years, not 27.5. The lesser is only for rental property scenarios.
