CUMIPMT Function

Summary

The Excel CUMIPMT function returns the cumulative interest paid on a loan between two periods. Microsoft defines it specifically as cumulative interest, which means the function isolates financing cost and excludes principal reduction.

That distinction matters in amortization work. A level-payment loan contains both interest and principal in every payment, but the mix changes over time. CUMIPMT lets you total only the interest portion for a selected range of periods.

This makes the function useful for loan review, refinancing analysis, cost-of-debt reporting, and any model that needs to compare financing burden across different segments of the repayment term.

Syntax

=CUMIPMT(rate, nper, pv, start_period, end_period, type)

rate is the interest rate per period, nper is the total number of periods, pv is the original loan amount, start_period and end_period define the range to total, and type indicates payment timing.

As Microsoft documents, the period numbers must be integers, and the same time unit must be used consistently for rate, term, and selected periods. A monthly loan requires a monthly rate and monthly start and end periods.

Arguments

• rate - Interest rate per payment period.
• nper - Total number of periods in the loan.
• pv - Present value, or original principal.
• start_period - First period to include in the interest total.
• end_period - Last period to include in the interest total.
• type - Payment timing: 0 for end of period, 1 for beginning of period.

Under Excel's default sign convention, CUMIPMT often returns a negative amount because interest payments are cash outflows from the borrower's perspective. That negative sign is expected and should not be mistaken for an error.

CUMIPMT vs Other Functions

CUMIPMT is closely related to PMT, IPMT, and CUMPRINC, but it solves a narrower question: how much interest was paid over a defined window?

Use CUMIPMT when the worksheet needs interest aggregated across a period range rather than only a single-period split.

Using the CUMIPMT Function

CUMIPMT is common in mortgage and loan analysis because it shows how financing cost behaves over time. Early loan windows often contain much more interest than later windows because the outstanding balance is still large.

That makes the function helpful for refinance reviews, debt-cost summaries, and any schedule where the user needs to compare the cost of carrying the same loan at different stages.

• Use CUMIPMT when the question is about total interest over a selected range.
• Keep the period unit consistent across rate, term, and period arguments.
• Interpret negative values as cash paid out, not as a formula problem.

Example 1 - First-Year Interest

This formula sums all interest paid in the first 12 months of a 30-year loan. The loan amount is 100000, the annual rate is turned into a monthly rate with 0.05/12, and the formula looks only at periods 1 through 12.

The result shows how much of the first year's payments went to interest instead of reducing the balance. That makes the example useful for beginners who want to see the real borrowing cost early in the loan, not just the monthly payment amount.

=CUMIPMT(0.05/12,360,100000,1,12,0)

Example 2 - Second-Year Audit

Calculating periods 13 through 24 isolates the second year's interest cost. The loan itself stays the same, but the time window moves forward to the second year of repayment.

This is helpful because the result can be compared with Example 1. In a normal amortized loan, the second-year interest should be lower, so the example teaches that CUMIPMT can answer questions about specific parts of the loan timeline, not just the whole loan.

=CUMIPMT(0.05/12,360,100000,13,24,0)

Example 3 - Interest Threshold Check

This logical test checks whether the first-year interest total is more negative than -10000. The negative comparison is intentional because the function usually returns cash paid out as a negative number.

So this example is really asking a simple question: did the first year's interest cost go past the limit? Instead of reading the raw total and judging it by eye, the formula returns TRUE or FALSE right away, which is easier to use in alerts and dashboards.

=CUMIPMT(0.05/12,360,100000,1,12,0)<-10000

Example 4 - Interest-to-Loan Ratio

Wrapping the result in ABS removes the sign so the interest total can be expressed as a positive share of the original principal. Dividing by 100000 then turns that dollar cost into a ratio of the loan amount.

This makes the example easier to read in a report because it answers a percentage-style question: how heavy was the interest cost compared with the amount borrowed? That is often more useful than a dollar amount alone when loans have different sizes.

=ABS(CUMIPMT(0.05/12,360,100000,1,12,0))/100000

Conclusion Recap

CUMIPMT is useful when you want to know how much interest was paid over part of a loan, not just in one payment. In this lesson, that meant comparing the first year with later periods, checking whether interest stayed under a limit, and turning the interest total into a ratio against the original loan.

The main thing to watch is the sign and the time unit. The result is often negative because it represents money paid out, and the rate, period numbers, and loan length all need to use the same unit or the answer will be misleading.

• Summary: CUMIPMT returns cumulative interest paid between two periods.
• Syntax: =CUMIPMT(rate,nper,pv,start_period,end_period,type).
• Core setup: Keep time units aligned and expect negative results under the default loan sign convention.
• Best use: Financing-cost analysis, amortization reviews, and interest-window comparisons.