Investors & landlords

I am assuming this is your first time dealing with rental property and the landlord experience. So please excuse me for the "language" if that assumption is wrong. Below I've posted information that you will "need". It also defines how you are required to treat property improvements, (sometimes referred to as capital improvements) and show the difference between improvements and repairs. (improvements are capitalized/depreciated, while repairs are treated differently depending on when that repair was done.)

You also mentioned that you "lived in the property" after closing. Understand that since at no time in 2020 was the property classified for any type of business use, your acquisition of the property on your 2020 tax return will be reported as the acquisition of a 2nd home. (assuming you already own your primary residence, that is.) The only things you will be allowed to deduct on your 2020 tax return will be property taxes and mortgage interest. They get claimed as an itemized expense on SCH A. Period. That's it.

Since the property was not "available for rent" at any time in 2020, you will not be reporting anything concerning this property on SCH E as a part of your 2020 tax return.  However, when you complete your 2021 tax return next year all those capital improvements (along with other acquisition costs you can not claim on your 2020 tax return) will be dealt with then. So KEEP ALL YOUR RECEIPTS AND SUPPORTING DOCUMENTS not only for the purchase/acquisition, but for the capital improvements you paid for also.

Rental Property Dates & Numbers That Matter.

Date of Conversion - If this was your primary residence or 2nd home before, then this date is the day AFTER you moved out, or the date you decided to lease the property – whichever is later.
In Service Date - This is the date a renter "could" have moved in. Usually, this date is the day you put the FOR RENT sign in the front yard.
Number of days Rented - the day count for this starts from the first day a renter "could" have moved in. That should be your "in service" date if you were asked for that. Vacant periods between renters count also PROVIDED you did not live in the house for one single day during said period of vacancy.
Days of Personal Use - This number will be a big fat ZERO. Read the screen. It's asking for the number of days you lived in the property AFTER you converted it to a rental. I seriously doubt (though it is possible) that you lived in the house (or space, if renting a part of your home) as your primary residence or 2nd home, after you converted it to a rental.
Business Use Percentage. 100%. I'll put that in words so there's no doubt I didn't make a typo here. One Hundred Percent. After you converted this property or space to rental use, it was one hundred percent business use. What you used it for prior to the date of conversion doesn't count.

RENTAL PROPERTY ASSETS, MAINTENANCE/CLEANING/REPAIRS DEFINED

Property Improvement.
Property improvements are expenses you incur that “better” the property. Basically, they retain or add value to the property. Expenses for this are entered in the Assets/Depreciation section and depreciated over time. Property improvements can be done at any time after your initial purchase of the property. It does not matter if it was your residence or a rental at the time of the improvement. It still adds value to the property.
To be classified as a property improvement, two criteria must be met:
1) The improvement must become "a material part of" the property. For example, remodeling the bathroom, new cabinets or appliances in the kitchen. New carpet. Replacing that old Central Air unit.
2) The improvement must retain or add "real" value to the property. In other words, when the property is appraised by a qualified, certified, licensed property appraiser, he will appraise it at a higher value, than he would have without the improvements.
There are rules that allow you to just flat-out expense and deduct some property improvements, if the total cost of the improvement was less than $2,500. It’s referred to as “safe harbor di-minimis” But depending on the specific situation, this may or may not be beneficial. Just be aware that not every property improvement that cost less than $2,500 qualifies for this. If this interest you, the rules can get complex. So a good place to start reading is on the IRS website at https://www.irs.gov/businesses/small-businesses-self-employed/tangible-property-final-regulations. The stuff on di-minimis starts about one page down.
Cleaning & Maintenance
Those expenses incurred to maintain the rental property and it's assets in the useable condition the property and/or asset was designed and intended for. Routine cleaning and maintenance expenses are only deductible if they are incurred while the property is classified as a rental. Cleaning and maintenance expenses incurred in the process of preparing the property for rent are not deductible.
Repair
Those expenses incurred to return the property or it's assets to the same useable condition they were in, prior to the event that caused the property or asset to be unusable. Repair expenses incurred are only deductible if incurred while the property is classified as a rental. Repair costs incurred in the process of preparing the property for rent are not deductible.
Additional clarifications: Painting a room does not qualify as a property improvement. While the paint does become “a material part of” the property, from the perspective of a property appraiser, it doesn’t add “real value” to the property.
However, when you do something like convert the garage into a 3rd bedroom for example, making a 2 bedroom house into a 3 bedroom house adds “real value”. Of course, when you convert the garage to a bedroom, you’re going to paint it. But you will include the cost of painting as a part of the property improvement – not an expense separate from it.