The instalment is only one line
The bond repayment is usually the largest monthly number, which makes the smaller lines easy to overlook. Municipal rates and charges, sectional-title levies, insurance and routine maintenance can materially change the cash left after payday.
For a free-standing property, create an allowance for minor repairs even when the building looks sound. For sectional title, read recent levy statements and ask whether a special levy is being discussed. Insurance requirements vary, so distinguish building cover from household contents cover.
Utilities may also behave differently after a move. A larger garden, pool, security arrangement or longer commute can turn a property choice into a transport and maintenance choice.
Use evidence, then leave margin
Request current figures where possible, but remember they are a snapshot. Rates can be adjusted, levies can rise and maintenance arrives unevenly. A budget should therefore contain both the best available estimate and a margin for movement.