What matters is that the amount contributed is based on the correct figure of W-2 wages and that they are made by the business tax return due date plus any timely filed business tax return extension.If the entity type is an LLC taxed as an S-Corporation (calendar year), the annual solo 401k contribution deadline is March 15, or September 15 if tax return extension is filed.

Now $685 was from damages that I could deduct from the previous tenant's security deposit.

It is not required, but you will have to be able to segregate for taxes.Many states also require that a separate bank account be used for the security deposits.Read your tenant-landlord law, get educated, you need to confidently know your processes.

Speak to a CPA regarding how/if you need to structure an LLC (I went with an umbrella policy instead of moving my property into a LLC) - this will be relevant when you file taxes and for depreciating your investment.3.

(i'll be securing the financing of it against my current portfolio with the assistance of a private lending partner. 

I might also recommend a security camera to catch people trespassing and if/ when they tear down or damage the fence.

Damage, to replace vinyl etc, is likely to be relatively small of 200-300 dollars.Would you fix it, and then keep the evidence to take out of their security deposit when they choose to move out, or would you confront them with the evidence, and post a bill for the amount of the work?

A small deposit is collected to secure the client on our schedule.

Anyone know of a good example of a real estate rental tax filing?

Absolute convinced real estate is the long term answer to financial security.