Ronald J. Solomon, D.D.S., Inc. v. Davisson, 2018 Ohio 2011

Davisson received dental services in January 2016 and signed a Financial Responsibility Agreement stating fees are due at time of service and that a 1.5% monthly (18% APR) late charge "may" be added after 60 days.
After insurance payments, $1,569 remained; Davisson disputed two procedures and did not pay. A magistrate reduced the billed amount by $178 and entered judgment for $1,391 plus late charges from an incorrect earlier date and post-judgment interest at 18%.
No party filed objections to the magistrate’s decision. The trial judge reviewed the transcript, adopted the $1,391 judgment, but rejected the 18% prejudgment/post-judgment interest, finding the agreement was permissive and not a binding contract for interest.
Solomon appealed the trial court’s rejection of the contractual 18% interest and the court of appeals considered whether the written Financial Responsibility Agreement constituted an enforceable contract under R.C. 1343.03(A).
The court of appeals held the Financial Responsibility Agreement was a written contract to which both parties assented and that a creditor is entitled to a contractual interest rate under R.C. 1343.03(A) when the contract provides for interest.
The court reversed in part, ruling Solomon was entitled to interest at the contractual 18% rate and remanded for the trial court to determine the correct date from which prejudgment interest ran (because the magistrate’s start date predated the contract and services).

Issue	Plaintiff's Argument	Defendant's Argument	Held
Whether the Financial Responsibility Agreement is a "written contract" under R.C. 1343.03(A) entitling the creditor to contractual interest	Agreement is a written contract evidencing mutual assent and sets the late-charge rate	Agreement language that a late charge "may" be added is merely permissive and does not create a binding contractual interest term	Agreement is a written contract; creditor entitled to contractual interest rate under R.C. 1343.03(A)
Whether the trial court properly refused to award prejudgment/post-judgment interest at 18%	Solomon argued he was entitled to contractual interest as a matter of law once judgment on contract claim was entered	Davisson argued the late-fee provision was permissive and plaintiff did not include interest in billing; trial court concluded plaintiff was not entitled to 18%	Trial court erred; prejudgment interest at contractual rate is mandatory when contract provides a rate and judgment is entered on the contract claim
Whether the magistrate’s chosen start date for late charges (pre-contract date) required correction despite no objections	Solomon relied on magistrate-calculated start date but record shows discrepancy	Davisson did not object; trial court failed to correct an obvious facial defect in magistrate’s decision	Court must remand to determine when money became due; trial court failed to catch the obvious error and must calculate interest from the correct date

Cusano v. Klein, 264 F.3d 936 (9th Cir. 2001) (describing characteristics of an open book account)
Minster Farmers Coop. Exchange Co. v. Meyer, 884 N.E.2d 1056 (Ohio 2008) (invoice or unilateral statement of interest does not satisfy written-contract requirement under R.C. 1343.03)
Hobart Bros. Co. v. Welding Supply Serv., Inc., 21 Ohio App.3d 142 (10th Dist. 1985) (creditor entitled to contractual interest where parties have a written contract providing an interest rate)
Dayton Sec. v. Avuto, 664 N.E.2d 954 (Ohio Ct. App. 1995) (prejudgment interest is required as a matter of law when judgment is entered on a contract providing an interest rate)
Royal Elec. Constr. Corp. v. Ohio State Univ., 652 N.E.2d 687 (Ohio 1995) (discussion of prejudgment interest in statutory context)
Fabrizi Trucking & Paving Co., Inc. v. City of Cleveland, 85 N.E.3d 279 (Ohio Ct. App. 2017) (amount of prejudgment interest depends on when money became due and payable)