Separate issue is only 13% of CA homeowners pay for earthquake insurance because it's so expensive and the deductible can be really high.What are your re-building costs in your area?

Financing OptionsParent Loan Options: Consider home equity loans, investment property mortgages, or co-signing a loan.Tax Implications: Speak with a financial advisor about potential deductions and capital gains.Rental Income Potential: Explore the option of renting out extra rooms to offset costs.5.

When you contribute to a Solo 401(k) as an employee, those contributions are made on a pre-tax basis, which means they are deducted from your gross wages before FICA taxes are calculated.

So, you get a tax deduction on the purchase price.

You get a deduction for the contribution, the gains grow tax-free and as long as you use the proceeds for health-related expenses the funds come out tax free as well. 

as a "donation" (translating to the benefit of taking a deduction for 2025).

"Good about deductions" sounds a lot like "doesn't make enough money to be a homeowner", so he should keep renting from someone else, and you should do what you're going to do with the money and wisdom you earned.Of course I don't know your son, but I think this is too dicey and you are too close to the situation.  

Since the HELOC was not used on improving the home you cannot deduct the interest, nor use that to offset your capital gain.

Federal Tax Benefits: You can claim depreciation deductions and may qualify for credits like Low-Income Housing Tax Credits or New Markets Tax Credits for eligible projects.3.

Leverage Tax Deductions:Claim tax deductions for mortgage interest, depreciation, HOA, insurance, and property taxes.