The charging method for IS resources is the way that the IS function allocates its costs to the users or business units that consume its services. The charging method can affect the behavior and incentives of the users and the IS function, as well as the efficiency and effectiveness of the IS resources. Therefore, choosing an appropriate charging method is an important decision for the IS function and its stakeholders.
One of the possible charging methods is to charge specific costs that can be tied back to specific usage. This means that the IS function tracks and measures the actual consumption of each user or business unit for each IS service, and charges them accordingly. For example, if a user uses 10 GB of storage space, 5 hours of CPU time, and 100 MB of network bandwidth, the IS function will charge them based on the unit costs of these resources. This charging method has the advantage of encouraging the most efficient use of IS resources, as it provides clear and accurate feedback to the users about their consumption and costs, and motivates them to optimize their usage and avoid waste or overuse. This charging method also aligns the interests of the IS function and the users, as both parties benefit from reducing costs and improving efficiency.
The other possible charging methods are:
* Total utilization to achieve full operating capacity: This means that the IS function charges a fixed amount to each user or business unit based on their proportion of the total operating capacity of the IS resources. For example, if a user or business unit has 10% of the total computing power allocated to them, they will pay 10% of the total IS costs. This charging method has the disadvantage of discouraging efficient use of IS resources, as it does not reflect the actual consumption or usage of each user or business unit, and does not provide any incentive to reduce costs or improve efficiency. This charging method also creates a mismatch between the interests of the IS function and the users, as the IS function benefits from increasing costs and capacity, while the users bear the burden of paying for them.
* Residual income in excess of actual incurred costs: This means that the IS function charges a markup or profit margin on top of its actual incurred costs to each user or business unit. For example, if a user or business unit consumes $100 worth of IS resources, the IS function will charge them $120, where $20 is the residual income for the IS function. This charging method has the disadvantage of discouraging efficient use of IS resources, as it increases the costs for the users and reduces their value for money.
This charging method also creates a conflict between the interests of the IS function and the users, as the IS function benefits from increasing costs and profits, while the users suffer from paying more than they should.
* Allocations based on the ability to absorb charges: This means that the IS function charges different amounts to different users or business units based on their ability to pay or their profitability. For example, if a user or business unit is more profitable or has a higher budget than another user or business unit, they will pay more for the same amount of IS resources. This charging method has the disadvantage of discouraging efficient use of IS resources, as it does not reflect the actual consumption or usage of each user or business unit, and does not provide any incentive to reduce costs or improve efficiency. This charging method also creates an unfair and arbitrary distribution of costs among the users or business units, as some pay more than others for no valid reason. References: 1: Charging Methods for IT Services - IT Process Wiki 2: IT Chargeback Methods - CIO Wiki 3: IT Chargeback - Wikipedia

The best method to determine if IT resource spending is aligned with planned project spending is earned value analysis (EVA). EVA is a technique that compares the actual cost, schedule, and scope of a project with the planned or budgeted values. EVA can help to measure the project progress and performance, and identify any variances or deviations from the baseline plan1.
EVA uses three basic values to calculate the project status: planned value (PV), earned value (EV), and actual cost (AC). PV is the amount of work that was expected to be completed by a certain date, according to the project plan. EV is the amount of work that was actually completed by that date, measured in terms of the budgeted cost. AC is the amount of money that was actually spent to complete the work by that date1.
By comparing these values, EVA can determine if the project is on track, ahead, or behind schedule and budget. EVA can also calculate various indicators, such as cost variance (CV), schedule variance (SV), cost performance index (CPI), and schedule performance index (SPI), to quantify the magnitude and direction of the variances. EVA can also forecast the future performance and completion of the project, based on the current trends and assumptions1.
The other options are not as effective as EVA in determining if IT resource spending is aligned with planned project spending. Option B, return on investment (ROI) analysis, is a technique that evaluates the profitability or efficiency of an investment, by comparing the benefits or revenues with the costs. ROI analysis can help to justify or prioritize a project, but it does not measure the actual progress or performance of the project against the plan2. Option C, Gantt chart, is a tool that displays the tasks, durations, dependencies, and milestones of a project in a graphical format. Gantt chart can help to plan and monitor a project schedule, but it does not show the actual cost or scope of the project3. Option D, critical path analysis, is a technique that identifies the longest sequence of tasks or activities that must be completed on time for the project to finish on schedule. Critical path analysis can help to optimize and control a project schedule, but it does not account for the actual cost or scope of the project4.
References:
* Earned Value Analysis & Management (EVA/EVM) - Definition & Formulae1
* Return on Investment (ROI) Formula2
* What Is a Gantt Chart?3
* Critical Path Method for Project Management