Lack of clarity with regards to house hacking taxes/depreciation

[Mandeep S.]

Hi,

It seems this is hotly debated on the internet.

If I have a single family home and rent rooms out, are proportions of common areas allowable in calculation of depreciation and expenses?

For example,

Let's say there's a 1000 sq foot house with two bedrooms - one for the tenant and one for the landlord.

100 sq foot is for landlord exclusive use.

100 sq foot is for tenant exclusive use.

800 sq foot is common areas (kitchen, living room, dining room, etc).

Is the business use 50% (100 + 400 [common area divided into 2]/1000) or 10% (100/1000)?

Most seem to say it would be 10%. "Only the exclusively used areas are considered rental areas. The common area is available to all and is not a factor in the allocation of expenses."

Others say it would be included. "If an expense is for both rental use and personal use, such as mortgage interest or heat for the entire house, you must divide the expense between rental use and personal use. You can use any reasonable method for dividing the expense."

It seems IRS Publication 527 (2023), Residential Rental Property would say it's 10% based on their example. Or maybe they oversimplified it, for sake of example?

"Example. You rent a room in your house. The room is 12 × 15 feet, or 180 square feet. Your entire house has 1,800 square feet of floor space. You can deduct as a rental expense 10% of any expense that must be divided between rental use and personal use. If your heating bill for the year for the entire house was $600, $60 ($600 × 10% (0.10)) is a rental expense. The balance, $540, is a personal expense that you can’t deduct."