The Relocation fund can be found in the Administration panel next to your city Suburb planning permissions. When relocating to a new Suburb, a Denarii payment is required which will be taken directly out of your relocation fund.
Invest Denarii into your relocation fund so that when you decide to relocate to new Suburbs you will have sufficient funds.
For example, migrating from the Homeland to the Inner Empire requires 30,000 Denarii from the relocation fund.