How Business Lines of Credit Work: The Mechanics Behind Revolving Capital

Most business owners understand that a line of credit lets you borrow money when you need it. Fewer understand how daily interest accrual actually works, what fees are embedded in the fine print, or what happens when the lender conducts its annual review. Those gaps are expensive—not because lenders hide them, but because the mechanics are rarely explained in plain terms.

This briefing covers the complete operational anatomy of a business line of credit: how draws work, how interest is calculated to the cent, what the fee table actually costs, and how lenders monitor your behavior after approval. Understanding these mechanics puts you in control of the cost of capital—which is one of the few costs in your business you can genuinely optimize.

The Revolving Credit Cycle Explained

A business LOC operates on a perpetual revolving cycle. Once approved, the facility remains open and available throughout the draw period—typically one to five years. The cycle has four stages:

What makes this structure powerful is stage four: when you repay drawn funds, your available credit limit restores. You don't reapply. You don't negotiate new terms. The capacity is simply available again. This is what separates a revolving line from every other credit instrument—it's a standing commitment from the lender, not a one-time disbursement.

For businesses with recurring cash flow gaps, this means a single approval can service years of working capital needs without the friction and cost of repeated loan applications.

Draw Mechanics: How to Access Funds

The draw process varies by lender, but the standard pathways are consistent across the market.

Online Portal Draws

Most modern LOC providers—banks and online lenders alike—offer an online dashboard where you initiate draws. You log in, enter the amount, confirm your linked bank account, and submit. Funds typically arrive via ACH transfer in 1–3 business days. Many established online lenders have built same-day or next-morning transfer capabilities for accounts with sufficient history.

Checkbook Access

Older bank LOC products sometimes issue a dedicated checkbook tied to the line. You write a check—to a vendor, to your operating account—and the LOC is drawn. This is less common now but still exists in traditional bank relationships, particularly for larger commercial lines.

Sweep Arrangements

Some commercial LOCs are structured as automatic sweep lines: when your operating account balance drops below a set threshold (say, $10,000), the LOC automatically advances funds to restore the minimum. When surplus funds accumulate, they automatically repay the drawn balance. Sweep arrangements remove the manual draw decision entirely and minimize idle interest accrual.

Draw Minimums and Maximums

Most lenders set minimum draw amounts—often $1,000 to $5,000—to prevent micro-draws that generate administrative cost. Maximum single draws are typically capped at the available credit balance. Some lenders also limit draw frequency (e.g., no more than one draw per day or three per week) on smaller facilities.

Interest Calculation: What You Actually Pay

This is where most borrowers lose precision. Interest on a business LOC is calculated daily on the outstanding balance—not monthly, not on the approved limit.

The Daily Interest Formula

Daily interest = (Annual APR ÷ 365) × Outstanding Balance

At 12% APR on a $75,000 drawn balance: (0.12 ÷ 365) × $75,000 = $24.66 per day. Over 30 days, that's $739.73 in interest. Over 90 days, $2,219.18.

The practical implication: every day you carry the balance, it costs money. Repaying even a partial amount—say, $25,000 of that $75,000—immediately reduces daily interest to $16.44. The incentive to repay quickly is direct and measurable, not abstract.

Variable vs. Fixed Rates

Nearly all business LOCs carry variable rates. The rate is expressed as a benchmark (typically the prime rate or SOFR) plus a margin set by the lender at origination. The margin reflects your creditworthiness and doesn't change during the draw period. But the benchmark rate floats.

In 2026, with prime at 7.5%, a borrower with a "prime + 3.5%" LOC is paying 11% APR. If prime rises to 8.5%, that borrower automatically moves to 12% APR—without any renegotiation. This rate risk is real and should factor into your decision to carry large LOC balances long-term.

Repayment: Minimum Payments vs. Full Repayment

LOC repayment is more flexible than term loan repayment—and that flexibility is both an advantage and a risk.

Minimum Payment Structures

Lenders typically require one of the following minimum payment structures:

• Interest-only: Pay only the accrued interest each month. The principal balance doesn't move. Common during draw periods, particularly on bank LOCs.
• Percentage of balance: Pay 1–2% of the outstanding principal balance monthly. On a $100,000 balance, that's $1,000–$2,000 monthly, before interest.
• Fixed minimum: A set minimum payment (e.g., $500/month) regardless of balance. Rare, and only on small revolving lines.

Why Full Repayment Matters

There are no prepayment penalties on virtually all business LOCs. This means paying the full drawn balance immediately upon receiving revenue is almost always the optimal strategy. Repay in full, stop interest accrual, restore credit capacity, and redraw only when the next need arises.

Businesses that use their LOC as revolving capital—draw, deploy, collect revenue, repay—pay dramatically less in total interest than businesses that treat the LOC as a long-term loan balance. Treat the drawn amount like a 30-day bridge, not a standing balance. For more on rates, see our LOC Interest Rates guide.

Draw Periods, Review Periods, and Renewal

A business LOC doesn't last forever without lender action. Understanding the lifecycle prevents surprises.

The Draw Period

The draw period is the window during which you can actively borrow. It runs 1–5 years depending on the lender and product type. During this period, you can draw and repay freely within your limit. The draw period is what's listed in your loan agreement as the "revolving period" or "commitment term."

Annual Reviews

Most bank LOCs are subject to annual review. Each year, the lender reassesses your financial condition: updated tax returns, recent bank statements, current accounts receivable aging, and updated financial statements. The review can result in three outcomes:

1. Renewal at same terms: Most common for borrowers in good standing.
2. Renewal with modified terms: Limit may increase (for improved financials) or decrease (for deteriorated financials). Rate margin may adjust.
3. Non-renewal: The lender declines to renew. Outstanding balances may be called or converted to term debt. This is rare but possible during economic downturns or significant borrower deterioration.

End of Draw Period

At the conclusion of the draw period, you typically cannot make new draws. Any outstanding balance either rolls into a repayment period (where you make scheduled payments to retire the balance) or must be repaid immediately. Most businesses renew the LOC before the draw period expires, avoiding a forced paydown.

For a complete application and renewal playbook, see How to Apply for a Business LOC.

Fee Anatomy: What's Hidden in the Fine Print

The stated APR is only part of the cost equation. Business LOCs carry a menu of fees that can meaningfully affect the all-in cost of capital.

The fee that catches most borrowers off-guard is the unused line fee. If you have a $500,000 LOC with a 0.25% unused line fee, and your average drawn balance is $100,000 (leaving $400,000 undrawn), you're paying $1,000/year for the privilege of having credit available. That's not unreasonable—it's essentially the cost of the commitment—but it should be factored into your all-in cost analysis.

To calculate your true all-in cost: add annualized fees to your interest expense, then divide by average outstanding balance. This gives you an effective annual rate that's directly comparable across lenders.

How Lenders Monitor Your LOC After Approval

Approval is not the end of lender scrutiny—it's the beginning of an ongoing monitoring relationship. Understanding what lenders watch for helps you manage the relationship proactively.

Financial Covenant Compliance

Most bank LOCs include financial covenants—contractual requirements your business must maintain. Common covenants include:

• Minimum DSCR (typically 1.20x–1.25x)
• Maximum debt-to-equity ratio
• Minimum liquidity (cash on hand or current ratio thresholds)
• Requirement to maintain primary banking relationship with the lender

Covenant breaches—even technical ones—give the lender the right to accelerate repayment (demand the full balance immediately) or reduce your credit limit. Lenders don't always exercise this right on the first breach, but they can.

Quarterly and Annual Financial Reporting

Bank LOC agreements typically require borrowers to submit quarterly or annual financial statements. This isn't optional—it's a contractual obligation. Failing to submit statements on time is itself a covenant breach. Larger LOCs (above $500,000) often require audited financials, not just internally prepared statements.

Behavioral Monitoring

Lenders watch how you use the LOC. Red flags include:

• Carrying the balance at or near the limit for extended periods (suggests the LOC is functioning as permanent debt, not revolving capital)
• Frequent overdrafts in your linked operating account
• Late or missed minimum payments
• Requesting draws immediately after repayments (suggests cash flow distress)

The best LOC relationship is one where you use the line actively but repay it regularly, demonstrate improving financials, and communicate proactively with your lender before problems arise—not after.

Frequently Asked Questions

How does interest work on a business line of credit?

Interest accrues daily on the outstanding drawn balance only. Your annual APR is divided by 365 to get the daily rate. At 12% APR on a $50,000 balance, your daily interest charge is approximately $16.44. You never pay interest on the approved limit—only on what you've drawn.

What is a draw period on a business line of credit?

The draw period is the window during which you can actively borrow—typically 1–5 years. During this time, you can draw and repay repeatedly. At the end of the draw period, the lender renews, converts, or closes the facility.

What fees does a business line of credit charge?

Common fees include: origination fee (0–3%), annual maintenance fee ($0–$1,500/year), draw fee ($0–2% per draw), and unused line fee (0.1–0.5% of undrawn balance annually). Always calculate all-in cost using stated APR plus annualized fees divided by average balance.

Can a lender reduce or cancel my business line of credit?

Yes. Lenders can reduce your limit or freeze your LOC if your financials deteriorate, if you breach a covenant, or during a credit tightening cycle. Annual reviews give lenders this reassessment opportunity. Maintaining strong financials and regular lender communication reduces this risk significantly.

What is the minimum payment on a business line of credit?

Minimum payments are typically interest-only on the outstanding balance, or 1–2% of the drawn principal. There are rarely prepayment penalties, so paying down the balance faster is almost always advantageous.

How long does a business line of credit last?

Most LOCs have draw periods of 1–5 years, with annual reviews determining renewal. Well-managed LOCs can remain open indefinitely through successive renewals.

What happens at the end of a draw period?

The lender reviews your account and typically renews the LOC, modifies terms, or requires repayment of any outstanding balance. Renewal is the most common outcome for borrowers in good standing.