A budget is a planning tool, and it is useful only if it states assumptions and is revised.
Phases. Case assessment and pleadings; early motions; written discovery; document collection, review and production; depositions; expert work; dispositive motions; pretrial; trial; and post-trial and appeal.
Assumptions stated. Number of custodians and estimated document volume; number of depositions taken and defended; number of experts; whether a dispositive motion will be filed; the trial length; and the schedule. A budget without assumptions cannot be assessed when it is exceeded.
Drivers. Document review is usually the largest single item and the most sensitive to scope. Model it separately with volume, review rate and cost per hour.
Contingencies. Discovery motions, a third-party dispute, an interlocutory appeal, and a scheduling change — each with a probability and a cost.
Reporting. Actual against budget by phase, monthly, with variance explanations and a revised forecast.
Revision points. After the pleadings close, after the scope of discovery is known, and after the key depositions. A budget prepared once and never revised is abandoned rather than exceeded.
Use. The budget informs the settlement analysis. A case worth less than the cost of trying it should be resolved, and the budget is what shows that.