Following are the similarities and differences between the solo 401k and the self-directed IRA.The Self-Directed IRA and Solo 401k SimilaritiesBoth were created by congress for individuals to save for retirement;Both may be invested in alternative investments such as real estate, precious metals tax liens, promissory notes, private company shares, and stocks and mutual funds, to name a few;Both allow for Roth contributions;Both are subject to prohibited transaction rules;Both are subject to federal taxes at time of distribution;Both allow for checkbook control for placing alternative investments;Both may be invested in annuities;Both are protected from creditors;Both allow for nondeductible contributions; andBoth are prohibited from investing in assets listed under I.R.C. 408(m)The Self-Directed IRA and Solo 401k DifferencesIn order to open a solo 401k, self-employment, whether on a part-time or full-time basis, is required;To open a self-directed IRA, self-employment income is not required;In order to gain IRA checkbook control over the self-directed IRA funds, a limited liability company (IRA LLC)must be utilized;The solo 401k allows for checkbook control from the onset;The solo 401k allows for personal loan known as a solo 401k loan;It is prohibited to borrow from your IRA;The Solo 401k may be invested in life insurance;The self-directed IRA may not be invested in life insurance;The solo 401k allow for high contribution amounts (for 2018, the solo 401k contribution limit is $55,000, whereas the self-directed IRA contribution limit is $5,500);The solo 401k business owner can serve as trustee of the solo 401k;The self-directed IRA participant/owner may not serve as trustee or custodian of her IRA; instead, a trust company or bank institution is required;When distributions commence from the solo 401k a mandatory 20% of federal taxes must be withheld from each distribution and submitted electronically to the IRS by the 15th of the month following the date of each distribution;Rollovers and/or transfers from IRAs or qualified plans (e.g., former employer 401k) to a solo 401k are not reported on Form 5498, but rather on Form 5500-EZ, but only if the air market value of the solo 401k exceeds $250K as of the end of the plan year (generally 12/31);When funds are rolled over or transferred from an IRA or 401k to a self-directed IRA, the amount deposited into the self-directed IRA is reported on Form 5498 by the receiving self-directed IRA custodian by May of the year following the rollover/transfer.Rollovers (provided the 60 day rollover window is satisfied) from an IRA to a Solo 401k or self-directed IRA are reported on lines 15a and 15b of Form 1040;Pre-tax IRA contributions on reported on line 32 of Form 1040;Pre-tax solo 401k contributions are reported on line 28 of Form 1040;Roth solo 401k funds are subject to RMDs;A Roth 401k may be transferred to a Roth IRA (Note that from a planning perspective, it may be advantageous to transfer Roth Solo 401k funds to a Roth IRA before turning age 70 ½ in order to escape the Roth RMD requirement applicable to Roth 401k contributions including Roth Solo 401k contributions and earnings.)

(you cannot roll over a percentage of a property etc.

To do so you need to rollover your retirement funds into what is known as Self-Directed IRA. 

@Dmitriy Fomichenko or others, I have seen a couple of opinions in different discussions that seem to contradict each other in regards to partnerships and future deals in that partnership also.An example is that I have been talking to a couple of potential investing partners that might want to roll over IRA or 401 funds into a SDIRA or SOLO401K to invest within buy-n-hold rentals. 

Hello Everyone,I’m scheduled to close on the sale of my single family rental the first week in May, and will have ~$250k in equity to roll-over into one or more replacement properties.I’d really like to hear other member’s perspectives on the pros and cons of purchasing small multifamily (2-4 units) with 30 year fixed financing vs larger multifamily (5-20 units) or a mixed use property with a commercial loan, which would likely be a 15 year loan term with monthly payments based on a 25 year amortization of the debt.This is my first 1031 Exchange, and I greatly appreciate your ideas, perspectives, or shared experiences. 

As for the rollover in 3 years, take into consideration your market projections, lease-up costs, and account for any added risk in the cap rate.

Do transfers and/or direct rollovers from on custodian to the other-institution to institution.

It may have already been mentioned, but on your tax advantaged accounts, it is VERY important that you do a direct rollover , Roth to Roth, regular IRA to Regular IRA etc so that you don't end up owing taxes.You might check to see what your cost basis is on your regular stocks, it might be worthwhile to sell some of them at a time.We personally have our retirement accounts with a discount broker and have some stocks and some ETF's within it.

I likely stand to get some sort of inheritance from him someday, and I think he'd roll over in his grave if I used it all for down payments on multiple properties with mortgages and leveraged up to my neck.

call your all your credit card companies and see if you qualify for a 24 or 18 month same as cash balance roll over, then pay the balance transfer fee and roll it over to buy time to seek traditional financing.