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//// Business · Collections

Late Fee Finder

Calculate the late fee on an overdue invoice and copy a paste-ready dunning email — three escalation tiers from friendly nudge to final notice.

Where this fits

📦 Business & Seller OpsGoing 1099FreelancersFounders

This tool lives inside Going 1099 and is most useful for freelancers and founders.

Corp Tax Rate21%
SE Threshold$400
FICA Cap 2024$168,600
You can charge $30.80 in late fees on this invoice. Total now owed: $2,530.80. It accrues another $1.23/day until paid.
Late fee
$30.80
Simple
Total owed
$2,530.80
Invoice + fees
Daily accrual
$1.23/d
$37/mo
Effective APR
18.0%
1.5%/mo

Interest method

Simple — flat % of original invoice per month

Simple: $30.80
Compound: $30.76

Invoice summary

Original invoice$2,500
Days overdue30d
Fee-accruing days25d
Late fee$30.80
Total owed$2,530.80

Legal notes

  • Only enforceable if in original contract
  • Most states cap at 1.5–2%/month (18–24% APR)
  • Grace periods are common practice (5–15 days)

Past-due email — paste & send

Subject

Past-due invoice $INV-2026-042 — $2,530.80

Body

Hi Acme Corp,

Invoice INV-2026-042 ($2,500) is now 30 days past due. Per our agreement, a late fee of $30.80 has been applied, bringing the total to $2,530.80.

Please remit payment within the next 7 business days. If there's an issue blocking payment, let's get on a quick call to sort it out.

Thanks,
Mitch
1

Fee-accruing days

Billable days = days overdue − grace period

= 30 − 5 = 25 days

0.82 months of accrual

2

Simple late fee

Fee = invoice × rate × months

$2,500 × 1.5%/mo × 0.821 months

= $30.80

Most freelance contracts use simple interest. Flat % per month, no compounding.

3

Compound late fee

Fee = invoice × ((1 + rate)^months − 1)

$2,500 × ((1 + 0.0150)^0.821 − 1)

= $30.76

Difference vs simple: -$0.04. Compounding requires explicit contract language.

4

Daily accrual rate

Daily $/day = invoice × rate ÷ 30.44

$2,500 × 0.0150 ÷ 30.44

= $1.23/day

That's $36.96/month at the current rate.

5

Total owed today

Total = invoice + simple late fee

= $2,500 + $30.80 = $2,530.80

6

Effective annual rate

APR = monthly rate × 12

= 1.5% × 12 = 18% APR

Most US states cap commercial late fees at 18–24% APR. Above that may be unenforceable.

UCC §2-718; state usury laws vary

Key insight

On a $2,500 invoice 30 days late, charging the standard 1.5%/month nets you $30.80 in fees. Each additional day is $1.23 more — gentle but persistent pressure to pay.

#ShowYourWork

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