Adjustments: refunds and unplanned charges
Record one-off amounts that came up after the booking was agreed — a refund to the guest/tenant, or a charge for something that wasn't in the price.
What an adjustment is
An adjustment is a one-off amount tied to a rental that was not part of the agreed price — a refund because something went wrong or the guest cut the stay short, a charge for damage, or a service added on the spot. Each entry has a concept, an amount (positive for a charge, negative for a refund) and a date. It appears in the rental's own record and, for long-term rentals, feeds the yearly income used in reports; it does not touch the property's expense ledger or the monthly payment schedule.
This is different from a booking's Extra fees. Fees you charge on every booking — cleaning, pets, linen — are part of the price and are set up in the rental form (and can be pre-loaded per property). Adjustments are for the things you could not plan for.
Rule of thumb: if you knew about it when you set the price, it's an Extra fee. If it came up afterwards, it's an adjustment.