Should Tenants Use Security Deposit Toward Rent

[Alexander F Pollock]

The tenant would like to use their security deposit towards May rent because May's late fees will cause them to be late for June & July. They would have to refill the security deposit, which would just cause them to still be late and probably incur more fees. Their lease is up in September. They do have a cosigner because of bad credit.  Should the cosigner pay and work it out between themselves? Thoughts on allowing them to use the security deposit?

Thanks in advance.