They should be tracked separately. Operating resources, official charges, professional work and household expenses have different purposes.
Ask what the estimate assumes
Clarify whether professional work includes reviewing the business plan and later changes. Check current official charges. Spending on premises or recruitment does not guarantee eligibility, and a business forecast is not a promise of immigration approval.
Costs also arrive on a schedule, and the schedule is what makes them manageable. Official charges fall due at filing; premises and recruitment commitments usually begin earlier and continue whether or not a decision has issued; professional fees tend to cluster at the filing and again at the extension, roughly a year apart. Put those three streams on one calendar before signing anything, because the common difficulty is not the total but a lease that starts months ahead of revenue and cannot be unwound.
Ask specifically whether the professional engagement covers the extension stage or ends at the initial approval, since the second review is where the evidence burden is heaviest. Confirm current official charges at the time of filing rather than relying on a figure quoted when planning began. Keep the receipts for each stream separately as well.
When the extension review asks what the operation actually spent on premises and staff, a folder already sorted by purpose answers in minutes rather than weeks.