Unit 13: Managing Costs

I. Cost Management Foundations

Project cost management is the process of estimating, budgeting, recording, and controlling the money required to complete project work. In scheduling software such as Microsoft Project, costs are calculated from task durations, resource rates, assignments, fixed charges, overtime, and actual progress.

A. Defining Properties and Conventions

The cost model connects the work breakdown structure, resource assignments, schedule, baseline, and progress data.

• Cost types: Project costs commonly include:
  • Work-resource costs: Labour or equipment cost calculated from assigned work and resource rates.
  • Material-resource costs: Quantity consumed multiplied by the material rate.
  • Cost-resource costs: A specified amount attached directly to an assignment, such as airfare.
  • Fixed costs: Charges entered directly against tasks, such as a permit fee.
• Core cost equation: The current cost of a task combines assignment costs and fixed costs.

Task Cost = Sum of Assignment Costs + Fixed Cost

• Work-resource calculation: Ordinary labour or equipment cost depends on regular work and the standard rate.

Regular Cost = Regular Work × Standard Rate

• Material-resource calculation: Material cost depends on the assigned quantity and unit rate.

Material Cost = Material Quantity × Cost per Unit

• Cost roll-up: Assignment costs roll up to tasks; task costs roll up through summary tasks to the project summary task.
• Baseline convention: A baseline stores the approved schedule and budget. Current cost is not a reliable performance reference until it is compared with baseline cost.
• Actual and remaining cost: Cost is divided according to completed and unfinished work.

Current Cost = Actual Cost + Remaining Cost

• Accrual method: A resource or fixed cost may accrue at the Start, End, or be Prorated across the duration of the work.
• Currency and time units: Rates may be entered as ₹800/day, $50/hour, or another configured currency and period; all calculations must use compatible units.

II. Total Cost Control

Total cost control determines where project money is allocated and whether task-level, resource-level, and project-level totals remain consistent.

A. Managing Total Costs for Tasks and Resources

Managing total costs for tasks and resources involves inspecting cost values at both the work-package level and the source-of-expenditure level.

• Task costs: In a task-oriented view, fields such as Cost, Fixed Cost, Actual Cost, Remaining Cost, and Baseline Cost show the financial position of each activity.
• Resource costs: In a resource-oriented view, total cost represents the cost of all assignments made to a person, equipment item, material, or cost resource.
• Assignment calculation: For a work resource without overtime, assignment cost is based on assigned work and the applicable standard rate.

Assignment Cost = Work × Standard Rate + Cost per Use

• Work is the scheduled labour or equipment effort.
• Standard Rate is the normal rate stored for the resource.
• Cost per Use is charged once for each assignment or use, depending on software behaviour.
  • Fixed task charges: A fixed cost is entered when expenditure does not depend on assigned work, such as a ₹5,000 inspection charge.
  • Rate tables: Multiple rate tables can represent different billing arrangements. For example, Rate Table A may contain an internal rate while Rate Table B contains a customer rate.
  • Effective dates: A resource rate can change over time; a rate table may specify ₹600/hour before 1 July and ₹650/hour from 1 July.
  • Task inspection: A cost table in a task view reveals activities with unusually high costs and summary tasks whose rolled-up totals exceed expectations.
  • Resource inspection: A resource cost table identifies expensive, overallocated, or incorrectly rated resources across all their assignments.
  • Worked example: A developer performs 24 hours at ₹800/hour, with a ₹1,000 cost per use.

Assignment Cost = (24 × ₹800) + ₹1,000 = ₹20,200

B. Managing Total Costs for the Entire Project

Managing total costs for the entire project means controlling the aggregate cost rolled up from every task, assignment, and fixed charge.

• Project total: The project cost is normally displayed through project statistics, reports, dashboards, or the project summary task.
• Bottom-up aggregation: The total is calculated from detailed entries rather than typed independently.

Project Cost = Sum of All Non-duplicated Task Costs

• Avoiding double counting: Summary-task costs already include their subtasks, so totals must not add both summary values and the same detailed values manually.
• Budget comparison: The principal project-level control compares current, baseline, actual, and remaining costs.

Projected Final Cost = Actual Cost + Remaining Cost

• Cost distribution: Grouping or filtering tasks by phase, department, deliverable, or resource group reveals where the budget is concentrated.
• Budget resources: Some scheduling systems permit budget cost or budget work values at the project summary level. These values establish funding limits but do not automatically replace detailed estimates.
• Contingency treatment: Management reserve should be represented consistently, such as a controlled task or budget allocation, rather than hidden by inflating unrelated resource rates.
• Validation: Before approving the total, verify resource rates, assignment units, calendars, fixed-cost accrual, task durations, and material quantities.

III. Cost Variance Control

Cost variance control measures departures from the approved baseline and locates the tasks, resources, or assignments responsible for them.

A. Managing Cost Variances for Tasks, Resources, and Assignments

Managing cost variances requires comparing current scheduled cost with baseline cost at progressively more detailed levels.

• Cost variance formula: Standard scheduling tools commonly calculate cost variance as current cost minus baseline cost.

Cost Variance = Current Cost − Baseline Cost

• A positive value means the current estimate exceeds the baseline.
• A negative value means the current estimate is below the baseline.
• Zero means no difference at the selected level.
  • Task variance: A task may exceed budget because its duration increased, more work was assigned, a costly resource replaced another, or a fixed cost changed.
  • Resource variance: A resource variance can result from a revised pay rate, additional assignments, overtime, or greater work than originally planned.
  • Assignment variance: Assignment-level examination isolates the specific task-resource combination causing a higher-level variance.
  • Hierarchical diagnosis: Begin with the project total, locate the affected summary phase, inspect its tasks, and then examine individual assignments.
  • Baseline discipline: Variance is meaningful only if the baseline represents the approved plan. Replacing the baseline merely to remove an unfavourable variance destroys the audit trail.
  • Worked example: If a task has a baseline cost of ₹40,000 and a current cost of ₹46,500:

Cost Variance = ₹46,500 − ₹40,000 = ₹6,500

The positive ₹6,500 indicates an expected overrun requiring investigation.

• Corrective action: Possible responses include reducing remaining work, replacing resources, changing scope through formal control, renegotiating rates, or accepting the variance with authorization.

IV. Timephased Cost Analysis

Timephased analysis shows not only how much money is planned or spent, but also when each amount occurs across days, weeks, months, or other reporting periods.

A. Managing Timephased Baseline (Budgeted) Costs and Actual Costs

Managing timephased baseline (budgeted) costs and actual costs involves comparing period-by-period planned expenditure with recorded expenditure.

• Baseline cost distribution: Baseline cost is stored across the scheduled periods existing when the baseline is saved.
• Actual cost distribution: Actual costs are assigned to periods according to completed work, actual work entries, assignment rates, fixed-cost accrual, and status updates.
• Timephased fields: Usage views can display Baseline Cost, Actual Cost, Cost, and Remaining Cost under daily, weekly, or monthly columns.
• Planned-versus-actual distinction:
  1. Baseline cost records the approved budget and timing.
  2. Actual cost records expenditure associated with completed work.
• Accrual effect: A ₹12,000 fixed cost accrued at Start appears at the task’s beginning; accrued at End it appears at completion; Prorated accrual spreads it over the task duration.
• Reporting periods: Weekly data helps operational control, while monthly data is often more suitable for management reporting and cash-flow forecasting.
• Status-date control: Actual and remaining values should be interpreted relative to the project status date, which separates reported progress from future work.
• Earned-value context: Timephased baseline and actual costs support earned-value measures, but actual cost alone does not show whether completed work justifies the expenditure.
• Data integrity: Actual work, completion percentage, assignment changes, and accounting imports must refer to compatible reporting dates to prevent misleading period totals.

V. Overtime Cost Calculation

Overtime costing separates premium-rate work from regular work so additional expenditure is visible without changing the resource’s normal rate.

A. Calculate Overtime Costs

Calculate overtime costs by explicitly identifying overtime work and applying the resource’s overtime rate.

• Overtime formula: Overtime cost is based only on work designated as overtime.

Overtime Cost = Overtime Work × Overtime Rate
Total Labour Cost = Regular Work × Standard Rate + Overtime Cost

• Overtime Work is the effort classified as overtime.
• Overtime Rate is the premium hourly rate.
• Regular Work is total work excluding overtime.
  • No automatic assumption: Work scheduled outside ordinary hours does not necessarily become overtime automatically; overtime work usually must be entered at assignment level.
  • Worked example: A resource completes 32 regular hours at ₹500/hour and 6 overtime hours at ₹750/hour.

Regular Cost  = 32 × ₹500 = ₹16,000
Overtime Cost = 6 × ₹750  = ₹4,500
Total Cost    = ₹20,500

• Scheduling effect: Overtime may shorten duration when it increases available effort, but it increases cost and must respect task type, assignment units, and resource calendars.
• Control requirement: Compare overtime cost with the financial effect of delay; overtime is justified only when schedule benefit or avoided loss exceeds its premium.

VI. Cost Updating and Control

Cost updating keeps the schedule’s financial data aligned with approved changes, reported progress, and actual expenditure.

A. Update Costs

Update costs by revising source data and progress records so the scheduling system recalculates dependent totals consistently.

• Automatic updates: Changes to work, duration, assignments, rates, material quantities, overtime, or fixed costs normally recalculate current and remaining costs.
• Actual cost calculation: When automatic calculation is enabled, actual cost is derived from reported progress and rates; manual actual-cost entry may require disabling that option.
• Rate updates: Change resource rates with correct effective dates so completed work retains historical rates while future work uses new rates.
• Progress updates: Record actual start, actual finish, actual work, remaining work, or percentage complete using one consistent reporting method.
• Assignment-level accuracy: Update the relevant assignment when only one resource’s work or cost changed; editing the whole task may distribute values incorrectly.
• Baseline protection: Routine updates change current and actual fields, not the approved baseline. Rebaseline only after authorized scope or budget change.
• Control cycle: Set the status date, enter progress, recalculate the schedule, inspect variances, validate timephased costs, document approved changes, and publish the revised forecast.
• Auditability: Preserve evidence for rate changes, manual actual costs, fixed-cost revisions, and baseline changes so each financial movement can be traced to an authorized event.