But what confused me was my apt rent less than $5 per sq foot so can I use the simple method? Many apt are less than $5 so I assume this is OK
I find nothing in IRS publication 946 or any other publication that says anything about limits based on what you pay for rent, mortgage, or anything else. The only limit I see is $5 per square foot on a maximum of 300 square feet. That means the most one can claim under the simplified method is $1,500 and that's it.
Take note also that your business must have the income to deduct it from, where that income would be taxable business income if you did not claim it. So if you're claiming 100 SQ FT at $5/SqFt which is $500, and you only have $400 of taxable business income to claim it against, that's all you get. The rest is just lost, and can not be carried over.