The formula for the annualized cost of invoice factoring is short: add up every fee, divide by the cash the factor advanced, then multiply by 365 over the days the invoice stayed open. Most of the work is in the inputs, because the fee is often quoted on the invoice's face value for each 10, 15 or 30 days while you only receive the advance. This guide walks through the steps, one invoice, and a year of $100,000 in monthly invoices.
The formula for the annualized cost of invoice factoring, step by step
With invoice factoring, the factor buys an invoice, pays you an advance, holds the remainder as a reserve, and returns the reserve minus its fees once your customer pays.
Annualized cost = (total fees ÷ cash advanced) × (365 ÷ days outstanding)
- Count the fee periods. Divide the days outstanding by the fee period, rounding up if the agreement bills a part period as a full one.
- Price the discount fee. Multiply the fee per period by the periods and by the fee base, which is often face value but can be the amount advanced.
- Add every other charge: wire or ACH fees, processing fees, and a share of any setup or monthly fees.
- Find the cash advanced: face value times the advance rate, minus any fees taken out of the advance.
- Divide total fees by cash advanced to get your cost for the time you held the money.
- Multiply by 365 ÷ days outstanding, counting from the day you receive the advance to the day the factor is paid.
The result is a simple (nominal) annual rate: one period's cost times the number of such periods in a year. The reserve never shows up as a fee because it's your money coming back, but it does shrink the base, so a 3% fee on face value is 3.75% of the cash at an 80% advance.
How to annualize invoice factoring fees charged every 10, 15 or 30 days
To calculate the annualized cost of invoice factoring fees charged every 10 or 15 days, start with the simplest case, a fee on face value with the invoice paid on the last day of a fee period. The six steps collapse into one line:
Annualized cost = fee % per period ÷ advance rate × (365 ÷ days in the period)
The table gives that multiplier for each 1% of fee.
| Fee is charged every | 80% advance | 85% advance | 90% advance |
|---|---|---|---|
| 10 days | 45.6 | 42.9 | 40.6 |
| 15 days | 30.4 | 28.6 | 27.0 |
| 30 days | 15.2 | 14.3 | 13.5 |
At an 80% advance, an assumed 1% per 10 days is 45.6% a year. So is 1.5% per 15 days (1.5 × 30.4) and 3% per 30 days (3 × 15.2), since all three charge 3% of face value for 30 days. They part ways when a customer pays mid-period and part periods are billed in full. Paid on day 35, the 10-day schedule charges 4% (52.1% a year), the 15-day schedule 4.5% (58.7%) and the 30-day schedule 6% (78.2%).
Annualized rate formula example: one $25,000 invoice paid on day 45
This invoice factoring fee example runs the annualized percentage rate formula on a single invoice, using these assumptions:
| Assumption | Value |
|---|---|
| Invoice face value | $25,000 |
| Advance rate | 80% ($20,000 advanced, $5,000 held in reserve) |
| Discount fee | 1% of face value per 10 days or part of 10 days |
| Wire fee | $25, taken out of the advance |
| Customer pays the factor | Day 45 |
- Fee periods: 45 ÷ 10 = 4.5, billed as 5.
- Discount fee: 1% × 5 × $25,000 = $1,250.
- Total fees: $1,250 + $25 = $1,275.
- Cash advanced: $20,000 - $25 = $19,975.
- Cost for the period: $1,275 ÷ $19,975 = 6.383%.
- Annualized: 6.383% × (365 ÷ 45) = 51.8%, simple.
Your reserve rebate is $5,000 - $1,250 = $3,750, so you collect $23,725 in total. The next table shows where the gap between the quoted 1% and 51.8% comes from.
| Calculation | Annualized |
|---|---|
| Quoted fee × periods in a year (1% × 36.5) | 36.5% |
| Measured on the cash advanced (÷ 80%) | 45.6% |
| Part period billed in full (5 periods over 45 days) | 50.7% |
| Adding the $25 wire fee | 51.8% |
Annual cost calculation example: $100,000 of monthly invoices
This annual cost calculation example assumes you send a factoring company $100,000 of invoices every month under the same contract: four $25,000 batches a month (48 a year), each paid on day 45, plus a one-time $500 setup fee taken from the first advance.
| Line | Amount |
|---|---|
| Invoices factored | $1,200,000 |
| Advances at 80% | $960,000 |
| Discount fees (5% of face value) | $60,000 |
| Wire fees (48 × $25) | $1,200 |
| Setup fee | $500 |
| Total cost for the year | $61,700 |
| Cost as a share of invoices factored | 5.14% |
| Cash advanced, net of wire and setup fees | $958,300 |
| Average funds in use ($958,300 × 45 ÷ 365) | $118,147 |
| Annualized cost ($61,700 ÷ $118,147) | 52.2% |
Each advance is repaid in 45 days and replaced by the next, so the factor's money in your business averages about $118,000. Hold the 5.14% against your margin: at an assumed 20% gross margin, it takes roughly a quarter of the gross profit.
Rerun it with customers paying on day 30 and discount fees fall to $36,000. The total drops to $37,700 (3.14% of invoices), average funds in use to $78,764, and the annualized cost to 47.9%. You'd save $24,000 while the rate drops only about four points, because under per-period pricing the dollars follow the days.
To estimate the advance and fee on your own outstanding invoices, try the invoice factoring cost calculator below.
▦Estimate your invoice factoring paymentsRun the numbers in the invoice factoring estimator →▸Effective annual rate formula, and how a disclosed APR differs
The effective annual rate calculation formula for invoice factoring compounds the period cost that the simple formula only multiplies:
Effective annual rate = (1 + total fees ÷ cash advanced) ^ (365 ÷ days outstanding) - 1
For the single invoice, 1.06383 raised to the power of 8.11, minus 1, is about 65.2%, against 51.8% simple. Use the simple figure against an APR on a loan or line of credit.
The simple version mirrors federal Regulation Z. Appendix J to 12 CFR Part 1026 (read October 6, 2026) says the APR "shall be the nominal annual percentage rate determined by multiplying the unit-period rate by the number of unit-periods in a year." For a single advance repaid in one payment, the term is the unit-period, and when a term under a year isn't a whole number of months the unit-periods per year are 365 divided by the days in the term.
At least two states apply that method to factoring. California's commercial financing disclosure regulations (10 CCR section 900 and following, DFPI final text) put an "Estimated Annual Percentage Rate (APR)" on a covered factoring disclosure, determined under Appendix J (sections 912 and 940). New York's 23 NYCRR Part 600 does the same in sections 600.3 and 600.12 (both texts read October 6, 2026). Both measure an offer against a size cutoff (equal to or less than $500,000 in California's section 921, $2,500,000 in New York's section 600.19) and other conditions, so ask whether your offer is covered.
A disclosed APR can still differ from your own figure in at least two ways:
- Timing. For a single-invoice disclosure, both rules tell the provider to assume the invoice is paid in full on the date it becomes due and payable (California section 941, New York section 600.13). By our reasoning, if your customer pays later than that under per-period pricing, you'd pay more dollars than the disclosure shows.
- The base. California defines the amount financed for a single factored invoice as "the original advance amount, minus any prepaid finance charge," which matches the cash-advanced base used here when the fees taken out of the advance are finance charges. New York's definition starts from "the receivables purchase price."
When an annualized rate distorts a short, one-off advance
An annualized rate tells you what the funding would cost if you carried it all year. A business that factors every month does, so the rate is a fair yardstick against a line of credit, but on a single short advance it can mislead.
Suppose a one-off quote carries a flat 3% minimum fee (an assumption) on the same $25,000 invoice, with the same 80% advance and $25 wire fee. The cost is $775 whether the customer pays in 10 days or 30. Annualized, that's 141.6% at 10 days and 47.2% at 30 days. Getting paid sooner didn't cost another dollar, yet the rate tripled, because the formula assumes you'd repeat the 10-day deal 36.5 times in a row.
For a one-off, weigh the $775 against what the cash earns or prevents, such as a supplier discount, a late fee or an order you'd otherwise turn down. Our guide to spot factoring covers single-invoice deals.
Putting two factoring quotes on the same footing
Ask each factor for the same inputs in writing:
- The fee percentage, the fee period, and whether a part period is billed in full
- The advance rate, and whether the fee is charged on face value or on the amount advanced
- Every add-on fee: setup, wire or ACH, processing, monthly minimums and termination
Then run the six steps at your customers' usual days to pay and again 15 days slower. Our breakdown of invoice factoring rates and fees lists the charges to look for, and factoring vs. a line of credit covers when a line fits better.
EQ Funding isn't a lender. We route one application to a network of lenders who compete for your business, which can give you more than one quote to run through this formula. Approval, pricing and terms vary by lender.