"Reverse" househacking refinance vs updates

[Lauren Feltz]

Hi All and thanks for your input!

My husband and I have a 4-plex in NH, which we bought in 2017 and have been fully renting out. We're selling our nearby primary home and downsizing to prepare for retirement by moving into the largest unit (thus 'reverse' househack).

We plan on refinancing once we officially move in to get a lower primary mortgage rate but have questions on the timing. We want to do a couple projects (update the kitchen, add in a new entrance, possibly go solar and go from septic to town sewer). Would it be best to do this before we refinance so that we can write off the costs as updates to the rental rather than our primary residence? If we have updates in the future after our refinance, is that all counted as updates to 'primary residence' rather than 'rental property' or does it depend on the unit updated? If its a big project like going on solar for all units, does that then get written as 1/4 personal cost and 3/4 rental property costs?

Thanks so much!
Lauren