Do I have to make any amendment to the lease.

You might be able to file amended returns, but it looks like only for the previous two years.Look at publication 527 and talk to your CPA more.

Tenant is liable for animal damages, must pick up after dog poops, clean out their kitty litter box regularly, obey leash laws, etc etc etc...(4) Have your lease amended saying if a tenant is prescribed a ESA during their lease they must first clear it with you and provide documentation and allow you to verify, failure to obtain written permission from landlord prior to introducing an ESA is a lease violation.(5) Also clarify that if an accommodation is a no pet accommodation, an verified and documented ESA requires the landlord to waive the no pet clause, only for that specific ESA. 

Actually, I would like to amend my comment above slightly.

Securities and Exchange Commission (SEC) amended the definition of an accredited investor.

These loan assumptions, when pre-negotiated, are contractual and cannot be amended.

The cost of any alteration undertaken to comply with any such requirements shall be in addition to the Contract price specified herein.Change Orders, Amendments, and Modifications Any subsequent amendment, modification, or Contract, which alters this Contract, and which is signed or initialed by Contractor and Owner, shall be deemed a part of this Contract and shall be controlling in case of conflict with any other provision in Contract.Extra Work and Changes If Owner, Construction Lender, or any public body or inspector directs any modification or addition to the work covered by this Contract, the charge for that extra work shall be determined in advance and the cost shall be added to the Contract price in addition to Contractor's usual fee for overhead and profit.

I'm hoping that the legislature here (with plenty of representatives that are NOT from super-lefty urban areas)  will be willing to consider that the downsides of allowing rent control would outweigh any benefits long term,  and there are other approaches to ease homelessness and housing availability crunch that should be considered instead (encouraging more housing construction, incentivising and underwriting riskier tenant pools instead of forcing landlords to take them; reinvestment in mental health and drug treatment programs and transitional housing, working with employers to site new job centers in underdeveloped/struggling areas, etc.)I'm certain that if the state constitution is amended Seattle will implement some kind of rent control.  

I guess I got the idea from other local area businesses (mainly bars) that have done the same thing - anytime a patron is caught on security cameras doing something egregious and causing damages they will post it out on social media - usually the person is quickly identified and they end up making amends and paying for the damages.All I'm seeking is our money back without having to lose half of it to a collections agency and secondly for him to knock his bullying off. 

Now there is an amended version that is up for vote by the state legislators.