If a separate mental health claim from years ago is finally approved, do I get back pay even though my combined rating stays the same?

Back pay is governed by the effective date assigned to the specific claim that was approved, not by whether your overall combined rating went up. Under 38 CFR 3.400 and 38 USC 5110, the effective date for an increase or a newly granted service-connected condition is generally the date VA received that claim, or the date entitlement arose, whichever is later, as long as the claim was continuously pursued (through appeals, higher-level reviews, or supplemental claims) rather than abandoned. If your depression and anxiety claim was filed in February 2021 and stayed in the system through appeals until it was finally granted, VA should assign an effective date at or near that 2021 filing date, and back pay is calculated from that date forward, regardless of when the PTSD claim was filed or approved.

The key nuance is that even though PTSD, depression, and anxiety are usually combined into a single mental health disability rating under 38 CFR 4.130 because they share overlapping symptoms, having no increase in your overall percentage does not automatically mean there's no retroactive payment. If the newly rated condition, when evaluated on its own merits, would have produced a higher combined rating during part of that retroactive period, or if it affects eligibility for something else, like TDIU, special monthly compensation, or dependents' benefits, there could still be money owed. If your combined rating genuinely stayed identical for the entire retroactive period because the umbrella rating was already capturing the same symptoms at the same severity, there may be no additional payment even though the claim itself was formally granted.

Disputes over effective dates are common and frequently contested on appeal, underscoring that this determination is often not straightforward even for VA raters themselves.

The concrete next step is to request your official decision letter (or the full rating decision) for the depression/anxiety grant, check the effective date and any "reasons and bases" section explaining how back pay was calculated, and if it doesn't reflect the 2021 filing date or doesn't address why no additional payment resulted, file a Decision Review Request (Higher-Level Review, VA Form 20-0996, or a Supplemental Claim, VA Form 20-0995) specifically challenging the effective date.