Why didn't my new 10% VA rating raise my overall combined disability percentage?

VA does not add individual disability percentages together in simple arithmetic. Instead, it uses the Combined Ratings Table found in 38 CFR § 4.25, which is based on the idea that each additional disability affects only the portion of the body that is still considered "efficient" or unimpaired after accounting for existing disabilities. This is often called the "whole person" or "efficiency" method of combining ratings.

Under this system, a veteran who is already rated at 80% has 20% of overall efficiency left. Adding a new 10% disability applies that 10% to the remaining 20%, not to the full 100%, which produces a combined value smaller than the simple sum of 80 and 10. VA then rounds that combined value to the nearest multiple of 10 for the final compensation rate. Depending on where the underlying number falls, that rounding can leave the overall rating unchanged even though a new individual rating was granted and is documented in the decision.

This is different from bilateral factor calculations, which apply only when disabilities affect paired body parts, and different from Special Monthly Compensation, which is a separate add-on system for certain severe or combined disabilities. A new 10% rating being "absorbed" into an already high combined rating is a known and expected outcome of the combined ratings formula, not an error, though veterans are entitled to see exactly how the math was applied.

For TMJ specifically, ratings are typically assigned under 38 CFR § 4.150, Diagnostic Code 9905, based on measured range of motion of the jaw (lateral excursion and interincisal range). A 10% rating is common for limited motion findings like those described in a typical exam, and that rating stands on its own merits even if it does not change the combined percentage.

Every decision letter includes a Combined Ratings Table calculation or at least a citation to the disabilities and percentages used; veterans can request the full rating decision document, which shows the intermediate combined value before rounding. If the math still seems off, it is reasonable to request clarification from a Veterans Service Officer (VSO) or to review the decision packet directly, since manual application of 38 CFR § 4.25 sometimes contains clerical errors that can be corrected through a request for a Higher-Level Review or by filing VA Form 20-0995 or 20-0996.

The concrete next step is to obtain and review the full rating decision letter, locate the Combined Ratings Table calculation section, and if the arithmetic appears inconsistent with 38 CFR § 4.25, bring it to a VSO or accredited representative for a formal review.