I normally will initiate a formal letter to my tenant on their intend to extend their tenancy by quoting the original TA document signed & stamped. In the letter, I will enclosed another draft letter for the tenant to agree on to extend the tenancy agreement based on the clause stated in the original TA, with all the conditions are to be maintained as per original condition of TA except for the new date of the extend tenancy period. My tenant will just need to sign back on the letter I drafted.