How VA combined-rating math works

VA combines individual evaluations against the remaining whole-person efficiency rather than adding percentages directly. VA combines the evaluations in sequence and rounds the final combined value to the nearest degree divisible by 10.

• Enter each individual service-connected evaluation separately.
• Review the ordered combination steps instead of relying on simple addition.
• Use the official VA combined-ratings table to verify the whole-person calculation and final rounding.
• Treat VMC results as an independent estimate and compare them with the official decision record.

5-, 10-, and 20-year rating protections

VA regulations provide different protections as an evaluation or service-connected status remains in effect over time. These are not special rules that apply only because a Veteran is rated 100%; each protection safeguards a different part of the award.

• 5 years — 38 CFR § 3.344: an evaluation that has continued at the same level for 5 years or more is considered stabilized for reduction purposes. VA must review the full record and generally must establish sustained improvement rather than rely on an isolated examination.
• 10 years — 38 CFR § 3.957: service connection that has been in effect for 10 years generally cannot be severed except for fraud or when the record shows the person did not have the required service or character of discharge. This protects service-connected status, not necessarily the percentage assigned.
• 20 years — 38 CFR § 3.951: an evaluation continuously rated at or above a level for 20 years generally cannot be reduced below that level except on a showing that the rating was based on fraud.
• Schedular total ratings — 38 CFR § 3.343(a): a total rating based on the severity of the condition, rather than individual unemployability, generally cannot be reduced absent clear error without an examination showing material improvement. VA must consider whether improvement occurred under the ordinary conditions of life.
• TDIU — 38 CFR § 3.343(c): a 100% compensation rating based on individual unemployability uses a different reduction standard. Actual employability must be established by clear and convincing evidence, and substantially gainful work alone generally cannot support reduction unless it is maintained for 12 consecutive months.
• The 5-, 10-, and 20-year clocks protect different things. Do not treat them as a single blanket guarantee that a rating can never be reviewed or changed.

Secondary explainers are provided for plain-language context only. The linked federal regulations and VA sources control when they differ.

Dependents and compensation rates

VA may pay an added dependent amount when a Veteran has a combined disability rating of at least 30% and an eligible spouse, child, or dependent parent.

• Ratings from 10% through 20% use Veteran-alone rates.
• Dependent categories and added amounts vary by rating and family configuration.
• Current rates can change after annual cost-of-living adjustments, so verify the effective rate year.

Understanding the bilateral factor

Under 38 CFR § 4.26, qualifying compensable disabilities affecting both arms, both legs, or paired skeletal muscles are combined first and receive a 10% arithmetic adjustment before the remaining combination steps.

• The factor is not a separate 10-percentage-point disability rating.
• Each side must generally have a compensable evaluation for the paired-extremity rule to apply.
• The current regulation includes a Veteran-favorable exception when excluding a disability produces a higher combined evaluation.

Special Monthly Compensation overview

Special Monthly Compensation is a higher or additional compensation rate associated with specific qualifying disabilities, combinations, or needs. A letter designation must be reviewed rather than inferred from a percentage alone.

• SMC-K is an additive payment variation subject to combination limits and exclusions.
• Higher SMC levels use specific statutory and regulatory criteria that are not established by calculator inputs alone.
• Always compare a modeled designation with the official VA award and current rate table.

Backpay and effective-date fundamentals

An effective date identifies when entitlement begins, while VA payment rules determine the first payable month. Different claim types and review outcomes can use different effective-date rules.

• Do not assume the diagnosis date, filing date, decision date, and payable date are the same.
• Historical estimates require the correct benefit events, rate years, and whole payable months.
• Document the official source for each accepted effective date before relying on a retroactive estimate.

Payment verification and award review

Payment verification compares accepted local records with a modeled entitlement timeline. It is a reconciliation aid, not a replacement for the official VA payment history or award letter.

• Separate recurring monthly payments from retroactive awards and adjustments.
• Attribute an award only when the source supports the affected period and issue.
• Keep unresolved differences visible rather than forcing them into a match.