Make sure the tenants sign off on the deposit amount so you can make sure it is transferred to you on sale.  

You are definitely spot on with your 60K low end 20% deposit estimation.

At closing the previous owner transferred the security deposit and last months rent as stated in the contracts. 

Felt good to deposit all those checks!

., 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.)

Get a non-refundable deposit from them at the signing of the assignemtn agreement and if possible a POF or bank statement showing they can pay in full at closing.

You should absolutely charge a pro-rated rent amount, which you should be able to deduct from the security deposit.

I do agree that for all parties a fixed price estimate is best (you need to know how to estimate properly).To be successful as a GC, things like getting a large deposit, making sure you are always staying ahead on billing and are spending clients money and not your own, marking up all costs at least 20% to cover OH&P, billing appropriately for change orders, not to mention staying up to date on latest building methods and continuing education, are the minimum requirements to last in this business.Of course you have to keep construction costs as low as possible when you are rehabbing a real estate project.  

Some get a weak deposit and some get a higher one.

Any tips on handling the tenant, the security deposit, and the current management company?