Q&A What happens at the end of a fixed term tenancy?
Q: Does a new tenancy agreement have to be drawn up at the end of a 12 month fixed term tenancy?
A: The short answer: no, it doesn't. Assuming the property is in England or Wales, once the original fixed term comes to an end, the tenancy continues as a "periodic tenancy", with the same terms and conditions as the original AST. This happens automatically and it's not necessary to fill out any extra paperwork. So long neither party does anything to bring the periodic tenancy to an end, it can continue indefinitely.
Some landlords and agents, however, prefer to draw up a new fixed term agreement. If a landlord wishes to increase the rent, this is a good opportunity to do so (and if, in these circumstances, the tenant refuses to agree to the new rent, they can be served with notice to vacate the property). But this is solely a matter for individual choice, and if nothing is done, that does not in itself create a problem for either tenant or landlord.