Expenses incurred for the furtherance of business, such as rent (commercial), telephone bill, stationery and so on, can be claimed under GST by recording them as purchases and not as expenses. To record such purchases, create a party ledger (party from whom such goods are procured) and ensure that GSTIN of the party is updated in the ledger. When the supplier uploads his GSTR-1, the details will appear in your GSTR-2A.