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Loan servicingIntermediate15 min

SOFR interest calculation for commercial loans

Understand the operational inputs behind term and overnight SOFR calculations, including spread, floor, dates, day count and review evidence.

Reviewed August 29, 2026 · Independent educational content

Learning outcome

You will be able to identify the inputs needed for a SOFR-linked accrual and explain why the governing documents—not a generic formula—control the result.

Foundation

Key concepts

What SOFR measures

SOFR is an overnight rate based on transactions in the US Treasury repurchase market and is administered by the Federal Reserve Bank of New York.

Contractual form matters

A facility may reference a forward-looking term rate, daily simple SOFR, compounded SOFR, a published average or another documented convention.

Rate components

The benchmark is commonly combined with a contractual margin and may also be subject to a floor or adjustment.

Calendar mechanics

Observation dates, lookback or lag, non-business-day treatment, day count and period boundaries can materially change an accrual.

In practice

Operating workflow

  1. 01

    Read the benchmark definition

    Identify the precise SOFR form, source, observation convention, fallback language and rounding rule in the agreement.

  2. 02

    Confirm principal and accrual dates

    Validate the balance history, start and end dates, inclusivity rules and any principal movements during the period.

  3. 03

    Collect approved rate data

    Use the institution-approved source for every required observation and retain evidence of the values and publication dates.

  4. 04

    Apply spread, floor and day count

    Construct the contractual rate and apply it to the eligible principal using the agreed fraction of a year.

  5. 05

    Recalculate independently

    Compare the system result with an independent estimate and investigate differences beyond the approved tolerance.

  6. 06

    Finalize and evidence

    Apply rounding, prepare notices or statements and retain the rate trail, calculation and approval evidence.

Risk and quality

Control checklist

  • The calculation uses the exact SOFR convention stated in the agreement
  • Rate observations come from an approved source and match the required dates
  • Principal changes and non-business days receive the documented treatment
  • An independent estimate agrees within the approved tolerance before release

Worked context

Illustrative simple-interest estimate

For a constant USD 1,000,000 balance, an illustrative annual rate of 6.00% and 30 eligible days on Actual/360, simple interest is USD 5,000. This is a teaching example only; compounding, observation shifts, floors, principal movements and contractual rounding can produce a different result.

Knowledge check

Test your understanding

Why should operations not calculate every SOFR loan using one standard formula?Show answer
SOFR can be incorporated through different contractual conventions. The agreement controls the benchmark form, observation timing, compounding or averaging, day count, spread, floor, fallback and rounding.

Source check

Authoritative references

Use these primary sources to verify benchmark or control-framework details. Your governing agreement and institution’s approved procedures still control each transaction.

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