NEVER borrow from a 401K, you are taking pre-taxed dollars and paying it back with after tax dollars, you do not get to return the loan with pre taxed dollars, in addition, some 401K plans do charge interest and maybe even fees, and lastly if you get laid off for some reason, it is a distribution with all the "fun consequences: tax at the last dollar rate, and if you are under 59.5 there is also the additional 10% penalty.Personally I like the HELOC, however you can also sell stocks and do tax harvesting there to offset gains if that is an option

Use umbrella insurance as an additional safeguard, especially if you opt not to form an LLC.Avoid S-Corp taxation for rentals, as rental income is passive and not subject to self-employment tax.

 - This is not double taxation.  

@Anita Z.I recommend finding an accountant who specializes in real estate taxation, tax planning and financial planning.

If you have a self directed IRA there are no tax consequences (but potentially various other issues), otherwise you will be subject to tax at the highest dollar rate as well as penalties if you are under 59.5 

After purchase the assessment office was given the survey and quickly reduced the acreage for taxation to 1.8 acres also. 

It is amazing how many times I have seen the cash flow represented as rent - PITI and to compound the issue they did not realize the ADU would increase their property tax.   At

A good real estate accountant can save you thousands of dollars by leveraging entity selection and formation, tax deductions, cost segregations, bonus depreciation and tax planning.I recommend finding an accountant who specializes in real estate taxation, business taxation, financial planning and tax planning.I would also recommend looking for a accountant willing to work with you throughout the year.

Do they know real estate business and real estate taxation?

A good real estate accountant can save you thousands of dollars by leveraging entity selection and formation, tax deductions, cost segregations, bonus depreciation and tax planning.I recommend finding an accountant who specializes in real estate taxation, business taxation, financial planning and tax planning.You may want to consider working with your accountant remotely to expand your options.I would also recommend looking for a accountant willing to work with you throughout the year.