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Invoice Due Date Calculator

Pick your invoice date and payment terms — get the exact due date, a 3-day follow-up reminder, overdue status, and a downloadable .ics calendar event.

Where this fits

📦 Business & Seller OpsGoing 1099Client ConversionFreelancersFounders

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

401(k) Limit 2024$23,000
Roth IRA Limit$7,000
S&P 500 Avg Return~10%/yr

Invoice Details

Payment Terms

PAYMENT DUE DATE

Sat, May 16, 2026

30 days remaining

Key Dates

Invoice Issued
Thu, April 16, 2026
Follow-Up Reminder
Wed, May 13, 2026

Send a friendly reminder here

Payment Due
Sat, May 16, 2026

30 days from today

Terms
Net 30
Manage proposals + invoices →
Pro tip: Include late fees (1.5%/mo is standard) and payment terms in every contract. Net 30 is the freelance standard — Net 15 is better if you can negotiate it.
1

Due date calculation

due_date = invoice_date + net_days

Thu, April 16, 2026 + 30 days

= Sat, May 16, 2026

Net 30 terms: payment expected within 30 calendar days of invoice. Industry median DSO (Days Sales Outstanding) is ~30 days for U.S. small businesses.

PYMNTS / QuickBooks 2024 — U.S. small business DSO benchmarks

2

Days until due (from today)

days_remaining = due_date − today

Sat, May 16, 2026 − Apr 16, 2026

= 30 days remaining

Comfortable window — follow-up date is set 3 days before due.

3

Follow-up reminder date

follow_up = due_date − 3 days

Sat, May 16, 2026 − 3 days

= Wed, May 13, 2026

3-day advance reminder reduces late payments by 30–40% (Fundbox 2023 study). Add to your calendar via the .ics download.

4

Late fee if 30 days overdue (standard 1.5%/mo on $5k invoice)

late_fee = principal × 1.5% × months_overdue

$5,000 × 1.5% × 1 month

= $75.00/month · $2.50/day

1.5%/month = 18% APR — legally enforceable if stated in your contract. Always include late fee terms in writing before the project starts.

Standard commercial late fee: 1.5%/mo (18% APR) — enforceable in all 50 states with contract disclosure

5

Float cost — opportunity cost of outstanding receivable (30-day term)

float_cost = invoice_amount × 5% APY ÷ 365 × net_days

$5,000 × 5% ÷ 365 × 30

= $20.55 on $5k invoice

Every dollar you're owed costs you ~$0.6849/day in lost investment return. Net 15 vs Net 30 saves $10.27 on a $5k invoice — a strong argument for shorter terms.

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