IRS Officers do have a transferable job, though the frequency is much less compared to IAS and IPS Cadres. As far as the posting is concerned, you ideally may be posted anywhere, any district in the respective state, however in most of the cases, Government Finance Offices, GST Bhawans, Tax Collector Offices are mostly located in District Headquarters and Townships, and rarely in Rural Areas. You really dont have an issue there, unlike IPS Cadre Officers who maybe posted at any corner of the State.