VA Combined Rating Math: 38 CFR 4.25, the Bilateral Factor, the Rounding Rules, and the Strategic Stacking That Actually Moves the Needle

VA disability ratings do not add. A veteran rated 50% for PTSD and 30% for a lumbar spine condition is not rated 80%. The veteran is rated, after the combined-ratings calculation under 38 CFR 4.25, at 65% — which then rounds to 65% (not down to 60% — the rounding rule moves to the nearest 10, and 65 is between the rounding boundaries depending on which subsection applies). This counter-intuitive math is the source of more misunderstanding among veterans, family members, and even VSO representatives than any other rule in VA disability law. It produces the classic confusion: "I have a 50% rating and a 30% rating; why is my check the 60% check?" And the corollary strategic question: "If I claim this secondary at 30%, what does that actually do to my rating, my check, and my eligibility for TDIU?"

This guide walks the math in detail. The substantive rule under 38 CFR 4.25 (the whole-person rule) and 38 CFR 4.26 (the bilateral factor). The rounding rules and why "30 + 30 = 51" is the practical shorthand the math actually produces. Four worked examples spanning the most common rating combinations. How Special Monthly Compensation (SMC) tiers layer on top of the combined rating. How TDIU intersects with combined ratings. And the strategic implication for which secondary chains actually move a rating versus which ones just add paperwork. It is written for veterans evaluating which secondaries to claim, veterans confused why their ratings combined to a lower number than they expected, and family members helping a veteran project the impact of a new claim or appeal.

Why doesn't the VA add ratings? The VA rates disability as the impairment of earning capacity caused by service-connected conditions, on a scale of 0% (no impairment) to 100% (total impairment). The math treats each successive rating as the impairment of the residual earning capacity that remains after prior ratings have been accounted for — what practitioners call the whole-person rule. A veteran cannot be more than 100% impaired, so each new rating is applied to the residual remaining after prior ratings, not added to a running total. The math is implemented through the combined-ratings table at 38 CFR 4.25, which is just the closed-form expression of the whole-person rule.

The Substantive Rule: 38 CFR 4.25 and the Whole-Person Method

The text of 38 CFR 4.25 establishes the procedure:

Disabilities resulting from common etiology or a single accident, disabilities affecting a single body system, e.g. orthopedic, digestive, respiratory, cardiovascular-renal, neuropsychiatric, multiple injuries incurred in action, or multiple disabilities incurred as a prisoner of war, will be considered by the rating agency as one disability. Except as otherwise provided, disabilities will be combined according to the combined ratings table.

The combined-ratings table — Table 1 in §4.25 — is a 100-by-100 matrix that gives the combined value of any two ratings. The table is not arbitrary; it is the closed-form expression of the formula:

Combined Value = (1 - (1 - r1) × (1 - r2)) × 100

Where r1 is the highest rating expressed as a decimal (e.g., 0.50 for a 50% rating) and r2 is the next-highest rating expressed as a decimal.

Worked algebraic example. A veteran with a 50% PTSD rating (r1 = 0.50) and a 30% lumbar spine rating (r2 = 0.30):

• 1 - r1 = 0.50 (residual capacity after PTSD)
• 1 - r2 = 0.70 (residual capacity after spine in isolation)
• Product = 0.50 × 0.70 = 0.35 (residual capacity after both)
• Combined Value = 1 - 0.35 = 0.65 = 65%

The combined value of 65% then goes through the rounding rule, which we'll cover in the next section.

For three or more ratings, the formula is iterative: combine the two highest, then combine that combined value with the next-highest, and so on, in descending order of rating. Practitioners refer to this as "starting with the highest and working down."

Three-rating example. A veteran with 50% PTSD, 30% lumbar spine, and 20% tinnitus (in descending order):

• Combine 50% and 30%: 1 - (0.50)(0.70) = 0.65 = 65%
• Combine 65% and 20%: 1 - (0.35)(0.80) = 1 - 0.28 = 0.72 = 72%
• Final combined: 72%, then rounded under §4.25 to 70%

The order matters: combining in descending order produces the same combined value as combining in any other order (the formula is commutative on individual pairs), but practitioners always work in descending order to make the table lookup straightforward.

The Rounding Rule: Why "30 + 30 = 51"

After all ratings have been combined, the final combined value is rounded to the nearest 10 under 38 CFR 4.25(a):

• Values 0-4 round down to the next-lower multiple of 10
• Values 5-9 round up to the next-higher multiple of 10
• The rating bands are 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%

So a combined value of 65 rounds to 70 (rounds up). A combined value of 64 rounds to 60 (rounds down — wait, 64 is in the 0-4 range, so it rounds down to 60). A combined value of 75 rounds to 80. A combined value of 74 rounds to 70.

The rounding rule has counter-intuitive effects at the boundaries. "30 + 30 = 51" is the practitioner shorthand for the math:

• r1 = 0.30, r2 = 0.30
• Combined Value = 1 - (0.70)(0.70) = 1 - 0.49 = 0.51 = 51%
• Rounded under §4.25: 51 falls in the 5-9 range above 50, so 51 rounds up to 50 — wait, no — 51 is between 50 and 60. The rounding band for 50 covers 45-54, and the band for 60 covers 55-64. So 51 rounds to 50.

So a veteran with two separate 30% ratings combines to 51%, which rounds to 50% — not 60%, despite "30 + 30" sounding like it ought to land at 60%. To get to 60%, the veteran needs a third rating that pushes the combined value to 55 or higher.

A second classic shorthand: "20 + 20 = 36." Two 20% ratings:

• 1 - (0.80)(0.80) = 1 - 0.64 = 0.36 = 36%
• Rounds to 40%

The combined-ratings table at §4.25 makes the calculation a lookup. For the most-common ratings, here are the combined values for two ratings (from the table):

First (across) / Second (down)	10%	20%	30%	40%	50%	60%	70%
10%	19	28	37	46	55	64	73
20%	28	36	44	52	60	68	76
30%	37	44	51	58	65	72	79
40%	46	52	58	64	70	76	82
50%	55	60	65	70	75	80	85
60%	64	68	72	76	80	84	88
70%	73	76	79	82	85	88	91

(All values are unrounded. Apply the §4.25(a) rounding rule to the final combined value after all ratings have been combined.)

The Bilateral Factor: 38 CFR 4.26

Bilateral conditions of paired extremities or organs receive an additional 10% added to the combined value of those bilateral conditions before they combine with the rest of the rating profile. This is the bilateral factor under 38 CFR 4.26:

When a partial disability results from disease or injury of both arms, or of both legs, or of paired skeletal muscles, the ratings for the disabilities of the right and left sides will be combined as usual, and 10 percent of this value will be added (i.e., not combined) before proceeding with further combinations, or converting to degree of disability.

The bilateral factor applies to:

• Both arms (or paired upper-extremity nerves)
• Both legs (or paired lower-extremity nerves)
• Paired skeletal muscles
• Sometimes paired organs (less commonly)

The factor does not apply to:

• Bilateral hearing loss (rated under a single combined audiogram-based rating, not paired)
• Bilateral conditions in different body systems (e.g., a left-knee condition and a right-shoulder condition — different paired regions)

Worked bilateral example. A veteran with bilateral lower-extremity radiculopathy at 20% each (right sciatic and left sciatic):

• Combine the two 20% ratings: 1 - (0.80)(0.80) = 0.36 = 36% (combined value before bilateral factor)
• Add the bilateral factor: 36 + (0.10 × 36) = 36 + 3.6 = 39.6, rounded to 40 (the bilateral-factor calculation rounds at the end of this step under M21-1 procedures — practitioners typically round to the nearest whole number here)
• The 40% bilateral-adjusted value then combines with the rest of the veteran's rating profile

The practical effect: a 36% bilateral combined value becomes a 40% bilateral combined value, and the additional 4 points often push the veteran into a different schedular band on the final combined rating. The bilateral factor is one of the most-undervalued mechanical features of VA rating math.

The §4.16(a) implication: a 40% bilateral-adjusted value satisfies the "single disability at 40% or more" prong of the schedular TDIU thresholds we walk in our TDIU guide. The bilateral factor can be the single mechanical move that opens the schedular TDIU path.

Worked Example 1: PTSD + Spine + Tinnitus, Adding a Sleep Apnea Secondary

A veteran is service-connected for:

• PTSD at 50%
• Lumbar spine at 30%
• Tinnitus at 10%

Combined value before secondary:

• 50% and 30%: 1 - (0.50)(0.70) = 0.65 = 65%
• 65% and 10%: 1 - (0.35)(0.90) = 1 - 0.315 = 0.685 = 68.5%, rounded to 69%
• Final combined: 69%, rounded to 70%

The veteran files for sleep apnea secondary to PTSD under our secondary conditions playbook, supported by a private nexus letter under our private nexus letter mechanics guide. The claim is granted at 50% (CPAP-required under DC 6847).

Combined value after secondary, in descending order: 50% PTSD, 50% sleep apnea, 30% spine, 10% tinnitus:

• 50% and 50%: 1 - (0.50)(0.50) = 0.75 = 75%
• 75% and 30%: 1 - (0.25)(0.70) = 1 - 0.175 = 0.825 = 82.5%, rounded to 83%
• 83% and 10%: 1 - (0.17)(0.90) = 1 - 0.153 = 0.847 = 84.7%, rounded to 85%
• Final combined: 85%, rounded to 90%

The secondary moves the veteran from 70% to 90%. In monthly compensation terms (using 2026 rates for a single veteran with no dependents, approximately): 70% pays roughly $1,800 per month; 90% pays roughly $2,300 per month. The secondary is worth roughly $500 per month, or $6,000 per year, in additional compensation — and at 90%, the veteran is one schedular increase away from 100% on the schedular path, with the §4.16(a) TDIU path open if the veteran is unable to maintain employment.

Worked Example 2: Spine + Bilateral Lower-Extremity Radiculopathy, with the Bilateral Factor

A veteran is service-connected for:

• Lumbar spine at 40%
• Right lower-extremity sciatic radiculopathy at 20%
• Left lower-extremity sciatic radiculopathy at 20%

Combined value, applying the bilateral factor:

• Combine the two 20% radiculopathy ratings (paired lower extremities): 1 - (0.80)(0.80) = 0.36 = 36%
• Apply the bilateral factor under §4.26: 36 + (0.10 × 36) = 39.6, rounded to 40%
• Combine the 40% bilateral-adjusted value with the 40% spine: 1 - (0.60)(0.60) = 1 - 0.36 = 0.64 = 64%
• Final combined: 64%, rounded to 60%

Without the bilateral factor — if the radiculopathies were treated as ordinary unpaired ratings — the math would be:

• 40% spine, 20% right radic, 20% left radic, in descending order
• 40% and 20%: 1 - (0.60)(0.80) = 0.52 = 52%
• 52% and 20%: 1 - (0.48)(0.80) = 1 - 0.384 = 0.616 = 62%, rounded to 60%

In this particular example, the rounding rule produces the same final 60% rating either way. But on a different rating profile — say, with a 10% tinnitus added — the bilateral factor would push the unrounded combined value from the 60s into the 70s, and the rounded rating would jump from 60% to 70%.

The lesson: always check the rating decision to confirm the bilateral factor was applied. Raters sometimes miss it, particularly when the bilateral conditions are rated in different decisions or under different diagnostic codes. Confirming the application is procedural housekeeping with substantive consequences.

Worked Example 3: Stacking Multiple Secondaries Onto a 50% PTSD Primary

A veteran is service-connected for:

• PTSD at 50%
• Lumbar spine at 20%
• Tinnitus at 10%

Combined: 50% and 20% = 60%, then 60% and 10% = 64%, rounded to 60%.

The veteran works through the highest-leverage secondary chains under our secondary conditions playbook:

1. Sleep apnea secondary to PTSD: granted at 50% (CPAP)
2. GERD secondary to PTSD medications: granted at 30%
3. Hypertension secondary to PTSD: granted at 10%
4. Erectile dysfunction secondary to SSRIs: granted at 0% with SMC(k) addition

Combined value with secondaries, in descending order: 50% PTSD, 50% sleep apnea, 30% GERD, 20% spine, 10% tinnitus, 10% hypertension, 0% ED:

• 50% and 50%: 1 - (0.50)(0.50) = 0.75 = 75%
• 75% and 30%: 1 - (0.25)(0.70) = 0.825 = 82.5%, rounded to 83%
• 83% and 20%: 1 - (0.17)(0.80) = 1 - 0.136 = 0.864 = 86.4%, rounded to 86%
• 86% and 10%: 1 - (0.14)(0.90) = 1 - 0.126 = 0.874 = 87.4%, rounded to 87%
• 87% and 10%: 1 - (0.13)(0.90) = 1 - 0.117 = 0.883 = 88.3%, rounded to 88%
• Final combined: 88%, rounded to 90%

Plus SMC(k) at approximately $130 per month for the ED.

The secondary stacking moved the veteran from 60% combined ($1,400 per month at 2026 rates for a single veteran) to 90% combined plus SMC(k) (approximately $2,430 per month). The annual difference is roughly $12,400 — and the veteran is now at the 4.16(a) TDIU threshold (single disability at 50%, combined rating at 90% — well above the 70% combined / 40% single threshold). If unable to work, the TDIU adjustment lifts compensation to the 100% rate plus SMC(k).

The strategic point: stacking secondaries is the single highest-leverage strategy for moving a combined rating, and the math compounds as the veteran approaches the higher bands. A veteran at 50% who adds a 50% secondary moves to 75%; the same veteran at 80% who adds a 50% secondary moves only to 90%. The marginal value of each additional rating diminishes as the combined rating climbs.

Worked Example 4: When a Secondary Does Not Move the Rating

A veteran is service-connected for:

• PTSD at 70%
• Lumbar spine at 40%
• Bilateral lower-extremity radiculopathy at 20% each (with bilateral factor)
• Sleep apnea at 50%
• Tinnitus at 10%

Computing the current combined value:

• Bilateral radiculopathy: 36 + (0.10 × 36) = 40%
• 70% PTSD and 50% sleep apnea: 1 - (0.30)(0.50) = 0.85 = 85%
• 85% and 40% spine: 1 - (0.15)(0.60) = 1 - 0.09 = 0.91 = 91%
• 91% and 40% bilateral radiculopathy: 1 - (0.09)(0.60) = 1 - 0.054 = 0.946 = 94.6%, rounded to 95%
• 95% and 10% tinnitus: 1 - (0.05)(0.90) = 1 - 0.045 = 0.955 = 95.5%, rounded to 96%
• Final combined: 96%, rounded to 100%

The veteran is at 100% schedular. Adding a 30% GERD secondary would have:

• 100% and 30%: well, 100% is total disability; the math caps at 100%. Adding any rating to a 100% schedular rating produces no additional schedular compensation.

The lesson: at the high end of the rating scale, marginal secondaries do not move the schedular rating. They can still serve other purposes — a 30% GERD secondary on a 100% schedular veteran can support an SMC(s) "100% plus 60%" claim under our TDIU guide, can support an aggravation claim if the GERD worsens, and can support an effective-date claim if the GERD predated the schedular 100% rating. But the secondary does not, on its own, change the monthly compensation check.

The strategic implication is to be selective in claiming secondaries on a high-end profile. Each claim is a procedural commitment — the C&P exam, the development time, the chance of an adverse C&P spilling onto the file. Secondaries that move the rating, or that support TDIU/SMC, are worth filing. Secondaries that do not move the rating may not be.

How SMC Tiers Layer on Top of the Combined Rating

Special Monthly Compensation (SMC) is paid under 38 USC 1114 and 38 CFR 3.350 at higher rates than the regular schedular compensation rate. SMC is tiered, and the tiers are designated by letter — SMC(k), SMC(l), SMC(m), SMC(n), SMC(o), SMC(s), SMC(p), SMC(r). The most relevant tiers for typical TDIU/combined-rating veterans:

SMC(k) — Loss of use of a creative organ. Approximately $130 per month additional. Triggered by erectile dysfunction (the most common chain), loss of use of a breast (women veterans), or analogous conditions. Stacks on top of any other compensation. Often available as a secondary connection chain under our secondary conditions playbook.

SMC(s) — Statutory housebound or "100% plus 60%." Approximately $400 per month above the regular 100% rate. Available where the veteran has either (a) one service-connected disability rated at 100% schedular plus an additional independent disability rated at 60% or more, or (b) is permanently housebound by reason of service-connected disabilities. Under Bradley v. Peake, 22 Vet. App. 280 (2008), a TDIU recipient can qualify for SMC(s) when the TDIU is based on a single disability at 100% and the veteran has an independent additional disability at 60% or more.

SMC(l) through SMC(o) — Higher tiers. Paid for severe disabilities — loss of use of one or more extremities (l), loss of one or more extremities plus loss of use of one extremity at a higher rate (m), and so on. The tiers are progressive; the highest tier (SMC(o)) is paid at roughly twice the rate of SMC(l).

SMC(p) — Intermediate steps. Paid at intermediate rates between adjacent SMC tiers when the veteran's disabilities meet the requirements for one tier but additional independent disabilities support a partial step toward the next.

SMC(r) — Aid and attendance enhancement. Paid at the highest SMC rates where the veteran requires the regular aid and attendance of another person and has additional severe disabilities.

The SMC framework is intricate and frequently misapplied at the rating-decision level. A veteran with TDIU and an additional independent 60% disability should always evaluate SMC(s) eligibility under the Bradley analysis. A veteran with ED secondary to a service-connected condition should always evaluate SMC(k). The additions are paid on top of the base rate and do not require an increase in the schedular rating.

How TDIU Intersects With Combined Ratings

TDIU pays at the 100% compensation rate without requiring a 100% schedular rating. The schedular rating is preserved on the rating decision; what changes is the payment amount. Several intersections worth tracking.

TDIU does not produce a 100% schedular rating. A TDIU recipient's schedular rating remains whatever it actually is — often 70%, 80%, or 90%. The 100% compensation rate is paid as the result of the TDIU adjustment. This matters for SMC(s) eligibility under Bradley, where the analysis turns on whether the schedular rating at any single condition is 100%.

Adding new secondaries to a TDIU recipient's profile does not change compensation. A veteran on TDIU is already at the 100% compensation rate. Adding a new secondary at 30% does not raise compensation. The secondary may have other consequences — supporting SMC(s), affecting effective dates, supporting aggravation claims — but the compensation check does not change.

A secondary that lifts the schedular rating to 100% can change the compensation profile. A TDIU recipient at 90% schedular who adds a 50% secondary may reach 100% schedular under §4.25 (90% combines with 50% to produce 95%, rounded to 100%). At that point, the rating is 100% schedular rather than 100% under TDIU. The base compensation does not change, but the SMC eligibility profile shifts: the veteran is now on the schedular 100% path, and any additional independent 60% disability triggers SMC(s) cleanly.

Effective-date implications matter. A new secondary granted with an earlier effective date (under our private nexus letter mechanics guide and the inferred-claim doctrine of Rice v. Shinseki) can produce retroactive payment if the secondary would have lifted the combined rating during the retroactive period. The math has to be run for each year of the retroactive period.

Strategic Implications: Which Secondaries Actually Move a Rating

Five strategic principles for evaluating which secondaries to claim, distilled from the math.

Principle 1: Marginal Value Decreases as the Combined Rating Climbs

A 30% secondary added to a 50% primary produces an unrounded combined of 65%. A 30% secondary added to an 80% primary produces an unrounded combined of 86%. The first scenario adds 15 points; the second adds 6 points. The marginal value of any additional rating decreases as the veteran's combined rating climbs.

Strategic implication: the highest-leverage time to claim secondaries is when the combined rating is in the 30%-70% range. Above 80% combined, only large secondaries (40% or higher) move the rating materially.

Principle 2: The Round-Up Boundaries Matter

A combined value of 64.4% rounds down to 60%; a combined value of 65.0% rounds up to 70%. The same veteran with the same conditions can be on either side of a 10-point rating band depending on whether one of the secondaries was rated at, say, 20% rather than 30%.

Strategic implication: when evaluating whether to claim a marginal secondary, run the math with the secondary at multiple plausible rating bands (often 10%, 20%, or 30%). If the secondary at the lower band leaves the veteran at a 64% unrounded combined and the secondary at the higher band lifts the veteran to a 65% unrounded combined, the difference is a 10-point rating band — and that band difference is roughly $300-$600 per month in 2026 compensation rates.

Principle 3: The Bilateral Factor Is Often Missed

Bilateral radiculopathy, bilateral knees, bilateral hearing-related conditions in paired structures — the bilateral factor under §4.26 adds 10% to the combined value of the bilateral pair. Raters miss it. Veterans miss it. The fix is procedural: review the rating decision, confirm the bilateral factor was applied, and file a Higher-Level Review on the rating-calculation error if it was not.

Our Supplemental Claim vs HLR guide walks the choice between the two. A bilateral-factor omission is a clean HLR target — the rating-calculation error is on the face of the decision.

Principle 4: Secondaries Below 10% Rarely Move the Rating

A 0% secondary rating produces no combined-rating contribution (the formula at r2 = 0.00 gives 1 - (1-r1)(1) = r1, no change). A 10% secondary rating produces a small contribution but typically does not cross a rounding boundary alone.

Strategic implication: a 0% rated secondary like erectile dysfunction (DC 7522) does not move the combined rating, but it triggers SMC(k) at approximately $130 per month. The strategic rationale is the SMC, not the rating math. Frame the claim accordingly.

Principle 5: Stacking Secondaries Across Body Systems Compounds Better

Multiple secondaries within a single body system — say, three spine-related secondaries — combine first as a single body-system rating and may not move the combined rating as much as expected. Multiple secondaries across different body systems (orthopedic, mental health, GI, cardiovascular) combine more cleanly and tend to move the rating more.

Strategic implication: when evaluating which secondary chains to claim from our secondary conditions playbook, prioritize chains that diversify across body systems — a sleep apnea secondary to PTSD, a GERD secondary to PTSD medications, a hypertension secondary to PTSD, a depression secondary to chronic pain — rather than three secondaries all within the orthopedic system.

A Practical Calculation Walk-Through

For a veteran or family member running the math by hand on a current rating profile, the procedure is:

1. List all current ratings in descending order. Include each rating with its diagnostic code and rating percentage. Identify any bilateral pairs.
2. Apply the bilateral factor to bilateral pairs first. Combine the two paired ratings as a pair under §4.25, then add 10% of the combined pair value, then carry the bilateral-adjusted value into the next combination. Round at the end of the bilateral step.
3. Combine in descending order. Take the highest two ratings, combine them under the §4.25 formula or table, and produce a combined value. Then combine that value with the next-highest, and so on.
4. Apply the rounding rule at the end. The final combined value rounds to the nearest 10. The intermediate combinations do not round (round only at the end, and after the bilateral-factor step).
5. Add SMC if applicable. SMC tiers are paid in addition to the base compensation, not combined into the schedular rating.

A free combined-rating calculator is available at zicron.claims/va/check — it accepts the rating profile, applies the bilateral factor where indicated, and projects the impact of adding new secondaries.

Common Errors in VA Rating Calculations

Five errors that come up repeatedly in our records review of rating decisions.

Error 1: Bilateral Factor Not Applied

The most common rating-calculation error. Raters miss the bilateral factor when the bilateral conditions are rated in different decisions, under different diagnostic codes, or when the bilateral nature of the condition is not flagged in the rating worksheet. The fix is a Higher-Level Review identifying the §4.26 omission with page references.

Error 2: Rounding Applied at the Intermediate Step

Raters sometimes round each intermediate combination rather than the final combined value. The error compounds across the calculation and can cost the veteran a 10-point rating band. Confirm that the rating decision shows the unrounded intermediate values and rounds only at the end.

Error 3: Same-Body-System Pyramiding

Under 38 CFR 4.14, the rating schedule prohibits "pyramiding" — paying multiple ratings for symptoms arising from the same disability or affecting the same body part. A rater who collapses two genuinely separate disabilities (say, lumbar spine and bilateral lower-extremity radiculopathy from the spine) into a single rating has misapplied the pyramiding rule. The radiculopathy is separately rateable as a secondary neurological manifestation of the spine condition under M21-1 procedures.

Error 4: SMC Tier Not Calculated

Raters frequently miss SMC(k) eligibility on a 0% ED secondary, miss SMC(s) eligibility under the Bradley analysis on a TDIU recipient, or miss intermediate SMC steps on complex profiles. The veteran's burden is to identify the SMC tier and raise it in the claim or appeal. Our TDIU guide walks the SMC framework in the TDIU context.

Error 5: Effective Date Misapplied After a Rating Change

When a new rating is granted with an earlier effective date, the rater must recompute the combined rating at each point in the retroactive period and pay the difference. Raters sometimes apply the new combined rating only prospectively, missing the retroactive payment owed. The veteran's burden is to verify the retroactive math. Run the combined-rating calculation at the start of the retroactive period (using the ratings in effect then plus the new rating) and confirm the back-pay reflects the differences.

Practical Implications

For the veteran with a current rating profile. Run the math. Confirm the bilateral factor is applied where applicable. Identify which secondaries from our secondary conditions playbook would actually move the rating into the next 10-point band, and prioritize those. Avoid filing marginal secondaries that will not move the combined rating unless they support SMC or TDIU.

For the veteran near the 4.16(a) TDIU thresholds. The single highest-leverage move is often a secondary that crosses a rounding boundary into the 70% combined rating (for the multi-rating prong) or that lifts a single rating to 40% via the bilateral factor (for the single-rating prong). Our TDIU guide walks the thresholds.

For the veteran with multiple bilateral pairs. Confirm each bilateral pair has the §4.26 factor applied. The most common omission is when the bilateral conditions were rated in different decisions over time. An HLR identifying the omission is procedural housekeeping with substantive consequences.

For the family member helping a veteran. Pull the rating decisions. Map the ratings into the descending order. Apply the bilateral factor where applicable. Run the combined-ratings table. Compare the result to the rating shown on the decision. If there is a discrepancy, the discrepancy is the case — and the HLR path is the venue.

Sources

• 38 CFR 4.25 — Combined ratings table
• 38 CFR 4.26 — Bilateral factor
• 38 CFR 4.14 — Avoidance of pyramiding
• 38 CFR 4.16(a) — Schedular TDIU thresholds
• 38 CFR 4.16(b) — Extra-schedular TDIU
• 38 CFR 3.350 — Special monthly compensation ratings
• 38 USC 1114 — Rates of wartime disability compensation (SMC tiers k through r)
• 38 USC 1155 — Authority for schedule for rating disabilities
• Bradley v. Peake, 22 Vet. App. 280 (2008) — TDIU and SMC(s) interaction
• Esteban v. Brown, 6 Vet. App. 259 (1994) — Pyramiding analysis
• Rice v. Shinseki, 22 Vet. App. 447 (2009) — Inferred TDIU and effective date
• M21-1 Adjudication Procedures Manual, Part III, Subpart iv, Chapter 6 — Rating procedures including combined ratings, bilateral factor, and pyramiding
• M21-1 Adjudication Procedures Manual, Part IV, Subpart ii, Chapter 4 — SMC adjudication
• VA Combined Ratings Table — Published in 38 CFR 4.25 and reproduced in M21-1

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