Interest on unpaid invoices in Delaware: a floating rate if no rate was agreed; the most you can set depends on the deal

Delaware's rate when no rate was agreed

What the text says: Federal Reserve discount rate (including any surcharge) + 5%, as of the time interest is due. Where no rate is expressed in the contract (6 Del. C. § 2301(a)).

How the rate moves: Legal rate and contract cap = Federal Reserve discount rate (incl. surcharge) + 5%.

• “Where there is no expressed contract rate, the legal rate of interest shall be 5% over the Federal Reserve discount rate including any surcharge as of the time from which interest is due;” — 6 Del. C. § 2301(a), read November 6, 2026

The most you can set in Delaware

For a homeowner: Federal Reserve discount rate + 5% (agreed in writing); no limit on loans or use of money over $100,000 not secured by the borrower's principal residence.

For a business customer: Federal Reserve discount rate + 5% (agreed in writing); no limit over $100,000 not secured by a principal residence.

• “(a) Any lender may charge and collect from a borrower interest at any rate agreed upon in writing not in excess of 5% over the Federal Reserve discount rate including any surcharge thereon.” — 6 Del. C. § 2301(a), read November 6, 2026
• “(c) Notwithstanding any other provision in this chapter to the contrary, there shall be no limitation on the rate of interest which may be legally charged for the loan or use of money, where the amount of money loaned or used exceeds $100,000, and where repayment thereof is not secured by a mortgage against the principal residence of any borrower.” — 6 Del. C. § 2301(c), read November 6, 2026
• “A retail seller or the holder of a retail installment contract may charge and collect a service charge in respect of a retail installment sale and may calculate such service charge in the manner and at the rate or rates specified in the contract governing the sale.” — 6 Del. C. § 4315, read November 6, 2026
• “there shall be no limitation on the rate of interest which may be legally charged for the loan or use of money, where the amount of money loaned or used exceeds $100,000,” — 6 Del. C. § 2301(a), (c), read November 6, 2026

Late fees in Delaware

What the text says: For consumer retail installment accounts (revolving), no delinquency or collection charge of any kind may be taken beyond the agreed service charge (attorney's fees excepted) (6 Del. C. § 4339); retail installment contracts likewise allow no charge beyond the service charge 'except as otherwise provided in this chapter' (§ 4317). Retail installment sales of goods or services (services for other than commercial or business use, including home-improvement services) by a retail seller payable in installments (6 Del. C. § 4301 definitions).

• “No fee, expense, delinquency, collection or other charge whatsoever shall be taken, received, reserved or contracted by the seller or holder of a retail installment account except as provided in this section.” — 6 Del. C. § 4339, read November 6, 2026
• “The service charge shall be inclusive of all charges incident to investigating and making the contract and for the extension of the credit provided for in the contract, and no fee, expense or other charge whatsoever shall be taken, received, reserved or contracted for except as otherwise provided in this chapter.” — 6 Del. C. § 4317, read November 6, 2026
• “(10) "Retail installment sale" or "sale" means the sale of goods or the furnishing of services by a retail seller to a retail buyer for a time sale price payable in installments.” — 6 Del. C. § 4301(10), (12), read November 6, 2026

Does Delaware want it agreed in advance?

Agreed in advance: yes, in the cases below. A contract rate must be 'agreed upon in writing' (6 Del. C. § 2301(a)).

• “Any lender may charge and collect from a borrower interest at any rate agreed upon in writing not in excess of 5% over the Federal Reserve discount rate including any surcharge thereon.” — 6 Del. C. § 2301(a), read November 6, 2026

Homeowners and businesses in Delaware

A homeowner buying services on installments is protected by the Retail Installment Sales Act (services for other than commercial or business use, including home improvement), which bars delinquency charges on revolving accounts beyond the agreed service charge. Repair of a single home is outside the construction payments-due rule.

• “(12) "Services" mean work, labor and services, for other than a commercial or business use, including services furnished in connection with the improvement of real property” — 6 Del. C. § 4301(12), read November 6, 2026

Prompt payment on private construction in Delaware

What the text says: Interest penalty at the Delaware legal rate (Fed discount + 5%) on late payments, compounding every 30 days; owner pays the contractor within 30 days of the end of the billing period. The payments-due rule (§ 3507) does not apply to public works, to erecting 6 or fewer residential units at once, to altering or repairing any single residential unit, or to someone buying materials for work on their own property.

• “(c) The interest penalty shall apply to the period beginning on the day after the required date and ending on the date on which payment of that amount due is made and shall be computed at the legal rate in effect at the time the obligation to pay a late payment interest penalty accrues. Any amount of an interest penalty which remains unpaid at the end of any 30-day period shall be added to the principal amount of the debt and thereafter interest penalties shall accrue on such amount.” — 6 Del. C. § 3506(c), read November 6, 2026
• “(a) Each construction contract awarded by an owner shall include: (1) A payment clause which obligates the owner to pay the contractor for satisfactory performance under the contract within 30 days of the end of the billing period;” — 6 Del. C. § 3506(a)(1), read November 6, 2026
• “(f) This section shall not apply to: (1) Public works contracts awarded under Chapter 69 of Title 29; (2) Contracts for the erection of 6 or fewer residential units which are under construction simultaneously, or for the alteration or repair of any single residential unit; or (3) Contracts for the purchase of materials by a person performing work on that person’s own real property.” — 6 Del. C. § 3507(f), read November 6, 2026

Work out a late charge in Delaware

Set your own rate.

What was not checked for Delaware

• The current Federal Reserve discount rate that Delaware's legal rate is built on was not found on a Delaware page, so that rate is given as the state's formula only.
• Several parts of Delaware's consumer credit chapter (6 Del. C. ch. 43) were not read for a late-charge rule.

Check Delaware's own text

Before you charge: read 6 Del. C. § 2301(a) and the other Delaware texts quoted on this page, or ask a lawyer. As of November 6, 2026.

This is a plain-words summary of each state's own laws as of November 6, 2026, not legal advice. Rules have exceptions. Check the state's own text, linked on every state's page, or a lawyer before you charge a late fee or interest.

Compare Delaware with every state's answer, or with its neighbours just below.

Next door to Delaware

• Maryland: 6% if none agreed, depends by agreement
• New Jersey: depends if none agreed, 16% for homes
• Pennsylvania: 6% if none agreed, depends by agreement

Official sources for Delaware

• 6 Del. C. § 2301(a) — read November 6, 2026
• 6 Del. C. § 4315 — read November 6, 2026
• 6 Del. C. § 4339 — read November 6, 2026
• 6 Del. C. § 4301(10), (12) — read November 6, 2026
• 6 Del. C. § 3506(c) — read November 6, 2026

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