The corporate evidence usually drives it. Establishing an affiliate relationship from ownership records takes more preparation than a straightforward parent-subsidiary case, and where the structure includes trusts or holding companies, corporate counsel may be involved before the petition is drafted. Filing fees should be read from the current USCIS fee schedule.
Budget for the corporate work, not just the filing
Ask the adviser to quote the corporate-evidence work separately from the petition itself, because that is where the variability sits. A company whose registers are current, whose filings are up to date and whose accountant can produce a clean ownership summary will spend far less than one that has to reconstruct a decade of share transfers. If the two companies use different accountants, expect coordination time as well. On the employer side, remember that this is a business cost of opening or staffing an American operation, and it is normal to ask the owners to confirm who is paying for what before the work begins. Keep the assumptions behind any quote in writing so that a later change in the structure does not become a disputed invoice.
Hypothetical example: Celeste, a water-treatment division manager, receives a flat quote before anyone counts her prior L classification time. Her cost review should begin with admission records and time outside the United States, because the seven-year L-1A ceiling may shorten the useful assignment or require documented recapture. The company can then price corporate records, foreign payroll proof, role evidence, translations, filing charges and optional expedited processing against the remaining period. Current government fees should be taken from official materials. Spending heavily on a petition package does not create additional L time, and a quote that omits ownership reconstruction or a new-office extension record may understate the work the company actually needs.