Accountant time is often the largest item. Rebuilding several years of mixed compensation, retrieving filings, and preparing a clear explanation takes professional hours before any immigration work begins. Legal review then has to read that reconstruction against the eligibility requirements.
Stage the accounting work first
Ask the accountant for a scoped summary of what was paid and how it was reported, then decide from that whether to take the file further. Paying for a full case build before the compensation history is understood risks spending on a record that turns out to have gaps. Keep official charges out of the estimate until the relevant step, and agree what happens to the fee if the qualifying year proves unsupportable.
Stage the spending so the accounting work produces a stopping point. A scoped summary of what was actually paid and how it was reported costs a fraction of a full case build and answers the question that determines whether a case exists at all. Only after reading it does drafting make sense.
Agree in advance what happens to the fee if the qualifying year proves unsupportable, and agree who bears the cost in a company where personal and corporate spending have never been strictly separated. Keep official charges out of the estimate until the relevant step, since they vary by route and change over time. Record the arrangement in writing so it need not be renegotiated under time pressure.