You are right to want to get rid of your tenant. Slow pay is the path to no pay. Your tenant wants a reduction when he does not even know how to pay on time. Post a pay or quit notice for the payment of rent. I believe the term is 7 days for New Hampshire. Do this the first day after the rent is due. The next day after the pay or quit notice expires, file for an eviction. Do not accept any rent after the eviction is filed. Especially do not accept a partial payment. The pay or quit notice should be posted on the door and sent by certified mail with a receipt request. Once your tenant is out there are other things to attend to. Post again when that time comes for information on how to handle the deposit.