Building a monthly rental forecast from job schedules and open POs

By RentalSpend · October 8, 2026

Forecast equipment-rental spend by job first, not by supplier bill. Tie scheduled work to cost codes, add the open PO balance, and then layer in contract-based extras such as delivery, fuel, and pickup charges.

The cleanest way to set a monthly equipment-rental forecast is to build it at the job or cost-code level, starting with the work that is actually scheduled for the month, then adding the remaining committed PO balance, and then adding only the extra charges your own agreement allows. That keeps the forecast tied to real work in the field instead of whatever has or has not been invoiced yet.^{[1][2][3][4][5][6]}

Illustrative example: one job’s October rental forecast

Here is a hypothetical example for one job in one month. The team wants to forecast October equipment-rental spend for a concrete and steel job that uses a crane, a telehandler, and a small loader. The job has already been scheduled, some rental costs are already committed through open POs, and the agreement allows several billable extras that should not be left out of the monthly view.^{[1][2][3][4][5][6]}

Build the forecast in order

1. Start with the monthly schedule and identify each task that will require rented equipment.
2. Assign each task to the right job, phase, cost code, or rental cost bucket.
3. Add the open PO balance for that equipment or job so committed spend is visible.
4. Layer in allowed extras such as delivery, pickup, fuel, environmental, taxes, or damage charges if your agreement treats them as billable.
5. Roll the job total up to the project or portfolio level and refresh it when the schedule or PO status changes.

Sources: ^{[1][2][3][4][5][7]}

Use scheduled work as the base of the forecast

The base of the forecast should be the work that is actually expected to happen during the month, not the total value of the rental agreement. If a piece of equipment is planned for only part of the month, forecast only the period it is expected to be on rent. That may mean a weekly or daily estimate, depending on how your team tracks the job.^[1][2][3][4]

This is why cost-code level forecasting is useful. Trimble and Procore both describe forecast reporting that starts at the cost-code level and then rolls up to higher levels. That structure lets you tie equipment demand to the task that needs it, instead of burying everything in one project total.^[1][2][3]

Treat the open PO balance as committed cost

Do not rely only on the invoices that have posted so far. Open project-related purchase orders and requisitions are commitments, and many project systems treat them as committed cost until they are canceled, closed, final-closed, or fully consumed, depending on the system rules. For rental forecasting, that means the remaining PO balance belongs in the committed bucket because it is already tied to the job.^[1][3][4]

If your AP or project controls team uses itemized PO balances, use the remaining balance logic in your system rather than recreating it by hand. One documented approach is PO quantity times unit price minus invoiced quantity times invoice unit price. That keeps the forecast aligned to what is still expected to hit the job.^[1][8]

Add only the extras your agreement really allows

Many rental agreements do not stop at the base rate. Published terms from major suppliers commonly say rental charges exclude delivery and pickup, refueling or fuel charges, transportation surcharges, environmental service charges, taxes, fuel taxes, and other miscellaneous charges. Some terms also allow repair or damage charges. Because terms vary by supplier, branch, and agreement, check your signed contract and rate sheet before you build these items into the forecast.^[5][7][6]

A practical way to handle this is to keep a separate line for each charge type that can appear on the invoice. That makes it much easier to tell whether the job is running over because the equipment stayed on rent longer than planned or because the supplier added billable extras.^[5][7][6]

Use off-rent timing, not just the planned end date

A job can finish before the billing stops. Some agreements allow charges to continue until the equipment is returned, picked up, cleaned, or otherwise accepted off rent. If that process is not complete, the forecast should assume the equipment is still billable under the contract until you have written off-rent confirmation or another accepted closeout record required by your agreement.^[5][7][6]

That is why month-end forecast updates should focus on three events: a schedule change, a PO balance change, or a change in the supplier’s billing status. If one of those changes, the forecast should move with it.^[1][2][3][4]

How to read the result

Once you have the monthly number, the useful question is not just whether it is accurate; it is what part of the number is still controllable. A large committed balance may simply reflect work already authorized. A large forecast-extras line may indicate that a job needs tighter off-rent control, better fuel return handling, or a review of the supplier agreement. Keeping the buckets separate gives finance, AP, and project teams a place to look when the month drifts.^{[1][2][3][4][5][7]}

What to do when the forecast and the schedule do not match

If the forecast is higher than the current schedule, check whether equipment is still on rent after the work moved or whether an open PO is sitting longer than the job needs. If the forecast is lower than the schedule, look for missing committed POs, unentered change orders, or billable extras that have not been added to the model. If the supplier keeps billing after the expected end date, confirm whether your contract requires an off-rent notice, pickup confirmation, or return acceptance before billing stops.^{[1][3][4][5][7][6]}

Practical next steps

Pick one active job and rebuild its next-month forecast using three lines: scheduled work, committed PO balance, and contract-based extras. Then compare that result with the current schedule and open PO list, and repeat the same method across the next few jobs so the monthly rollup is built from the same logic everywhere.^{[1][2][3][4][5][7]}

Common questions

Should I forecast from the PO amount or the invoice amount? Use the open PO balance for committed cost, not just the invoice amount. The invoice only shows what has posted so far; the open PO balance shows what is still expected to hit the job, subject to your system rules.^[1][3][4]

Do delivery and pickup charges belong in the forecast? Usually yes if your signed agreement treats them as billable extras or separate service charges. Check your contract and rate sheet, because terms vary by supplier and branch.^[5][7][6]

Should taxes and fuel-related charges be included? Include them when your agreement or local rules say they will be billed to the job. Do not assume they are part of the base rental rate.^[5][7][6]

How often should the forecast be updated? Update it whenever the schedule changes, the PO balance changes, or the supplier’s off-rent or billing status changes. Weekly review is common on active jobs, but your team can set a different cadence.^[1][2][3][4]

What if the equipment has not been picked up yet? Do not assume the rental is over until the off-rent or return process is complete under your agreement. Charges may continue until the supplier accepts the equipment off rent.^[5][7][6]

What is the best structure if our company tracks by cost code? Build the forecast at the cost-code level, then roll it up to the project or portfolio total. That is the most practical way to reconcile schedule, commitments, and actuals in one monthly view.^[1][2][3]

← All resources