#interest
Calculate and track interest income and expenses
How ag equipment dealerships should track floor-plan interest per unit, re-mark trade-in inventory as used tractor prices fall, and measure parts-department absorption rate — where the national average sits in the mid-60s percent and under 50% signals trouble.
Divide 72 by an annual rate and you get the approximate years for money to double: $50,000 at 9% doubles in 8 years, while a 24% credit card balance doubles what you owe in 3. How business owners can use the Rule of 72 to compare investments, price debt, and gauge inflation's drag on idle cash.
The Rule of 78 front-loads loan interest so a lender on a 48-month, $8,000-interest equipment loan has earned about 74% of that interest by month 24 — gutting the savings from early payoff. Here's how precomputed loans work, where they're still legal under 15 U.S.C. § 1615, and how to spot one before you sign.
As of mid-2026, competitive business savings accounts pay roughly 3.5%–3.75% APY while the national average sits near 0.4% — a $150,000 idle balance in a 0.01% checking account forgoes about $5,000 a year. A timeline-based framework for placing tax reserves, operating buffers, and balances above the $250,000 FDIC limit into high-yield savings, CD ladders, ICS/CDARS sweep programs, and Treasury money market funds.
A below-market loan triggers Section 7872, which treats forgone interest as taxable income to the lender even when no cash changes hands. This guide covers the $10,000 and $100,000 de minimis exceptions, the gift tax connection, and how charging the AFR avoids the whole problem.
The OBBBA restores a personal car-loan interest deduction—up to $10,000 per year, above-the-line, for tax years 2025 through 2028—on new U.S.-assembled vehicles financed after December 31, 2024. Mechanics covered include the MAGI phase-out starting at $100K single / $200K joint, Form 1098-VLI reporting beginning in 2026, mandatory VIN entry on Form 1040, and edge cases for refinances, trade-ins, leases, and co-signers.
Section 163(h) decides whether your largest Schedule A line is a $14,000 deduction or an $8,500 one. Here is how the permanent $750,000 TCJA cap, the grandfathered $1 million pre-2018 loans, the HELOC "substantial improvement" rule, and the 2026 return of the mortgage insurance premium deduction actually work — with worked examples and the records you need on audit.
A Section 6603 deposit freezes IRS underpayment interest on contested tax while preserving your appeal, Tax Court, and withdrawal rights. This guide covers the written designation under Rev. Proc. 2005-18, when a deposit beats a payment, LIFO withdrawal mechanics, and the procedural traps that turn planned deposits into accidental payments.
A Section 6603 deposit halts interest on a disputed IRS liability without paying the tax, conceding the position, or forfeiting Tax Court access. Revenue Procedure 2005-18 spells out the mechanics—a written designation that names the tax, year, amount, and basis for disputability.
A practical 2026 playbook for small businesses using a Treasury-bill ladder to earn ~3.66% on idle operating cash, capture the state and local tax exemption on Treasury interest, and keep the bookkeeping clean.
Informal family or employer loans below the AFR trigger IRC Section 7872 imputed interest, treated as gifts, wages, or dividends.
OBBBA permanently restored the EBITDA-based ATI calculation for Section 163(j) starting in 2025, expanding deductible business interest for capital-intensive companies. A guide to the 30% cap, the ~$31M small business exemption, the 35% syndicate trap, EBIE allocations from partnerships, S-corp differences, and Form 8990 reporting.
