diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6c850bcb..cef5b75a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -32,6 +32,10 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/).
 
 ### Added
 
+- **`RecommendationParams.RIAccountScope`:** selects the Cost Explorer account
+  scope (`linked` default, or `payer`) for Reserved Instance recommendations,
+  mirroring `SPAccountScope`. Empty keeps the previous linked behaviour; an
+  unknown value is rejected (#508).
 - **`recommendations.RederiveFamilyCoverage`:** recomputes the family-wide
   RDS `ProjectedCoverage` that family-NU sizing wrote, after a caller changed
   `Count` (`--max-instances`, count override, duplicate-RI dedupe). It shares
diff --git a/pkg/common/types.go b/pkg/common/types.go
index ab7ad6bb..489d6fc4 100644
--- a/pkg/common/types.go
+++ b/pkg/common/types.go
@@ -554,6 +554,10 @@ type RecommendationParams struct {
 	// recommendations: "linked" or "payer" (case-insensitive). Empty means
 	// linked. Payer scope only applies to a management account.
 	SPAccountScope string
+	// RIAccountScope selects the Cost Explorer account scope for Reserved
+	// Instance recommendations, with the same values as SPAccountScope:
+	// "linked" or "payer" (case-insensitive). Empty means linked.
+	RIAccountScope string
 	// ExperimentalGCPPlanTerm (GCP Compute Engine only, ignored elsewhere)
 	// takes the CUD term from the recommendation's root Commitment plan
 	// instead of Term. EXPERIMENTAL: the payload shape is unverified against a
diff --git a/providers/aws/go.mod b/providers/aws/go.mod
index 4dabcff9..a1df881b 100644
--- a/providers/aws/go.mod
+++ b/providers/aws/go.mod
@@ -3,7 +3,7 @@ module github.com/LeanerCloud/cloud-commitments-go/providers/aws
 go 1.26.9
 
 require (
-	github.com/LeanerCloud/cloud-commitments-go/pkg v0.0.0-20261018003623-541e05e5fd29
+	github.com/LeanerCloud/cloud-commitments-go/pkg v0.0.0-20261019223052-37131464e21b
 	github.com/aws/aws-sdk-go-v2 v1.41.5
 	github.com/aws/aws-sdk-go-v2/config v1.29.12
 	github.com/aws/aws-sdk-go-v2/credentials v1.17.65
diff --git a/providers/aws/go.sum b/providers/aws/go.sum
index 22694c7a..8c9ae9ec 100644
--- a/providers/aws/go.sum
+++ b/providers/aws/go.sum
@@ -1,5 +1,5 @@
-github.com/LeanerCloud/cloud-commitments-go/pkg v0.0.0-20261018003623-541e05e5fd29 h1:QJkoZBHkwjvMGplDb1TcuBy3HdYPxlZ+AyR/7QEU8Hc=
-github.com/LeanerCloud/cloud-commitments-go/pkg v0.0.0-20261018003623-541e05e5fd29/go.mod h1:SCDEgHG6evjPh0RsoXof+J3aMmGXNFMrwbJIle7rMpQ=
+github.com/LeanerCloud/cloud-commitments-go/pkg v0.0.0-20261019223052-37131464e21b h1:0JK0YAYhPL3nOD+UKZZlcCtsvJ3yhjj1JeHZWgAll8g=
+github.com/LeanerCloud/cloud-commitments-go/pkg v0.0.0-20261019223052-37131464e21b/go.mod h1:SCDEgHG6evjPh0RsoXof+J3aMmGXNFMrwbJIle7rMpQ=
 github.com/aws/aws-sdk-go-v2 v1.41.5 h1:dj5kopbwUsVUVFgO4Fi5BIT3t4WyqIDjGKCangnV/yY=
 github.com/aws/aws-sdk-go-v2 v1.41.5/go.mod h1:mwsPRE8ceUUpiTgF7QmQIJ7lgsKUPQOUl3o72QBrE1o=
 github.com/aws/aws-sdk-go-v2/config v1.29.12 h1:Y/2a+jLPrPbHpFkpAAYkVEtJmxORlXoo5k2g1fa2sUo=
diff --git a/providers/aws/recommendations/client.go b/providers/aws/recommendations/client.go
index 08256220..3007a1a8 100644
--- a/providers/aws/recommendations/client.go
+++ b/providers/aws/recommendations/client.go
@@ -145,12 +145,17 @@ func (c *Client) GetRecommendations(ctx context.Context, params *common.Recommen
 		return c.getSavingsPlansRecommendations(ctx, params)
 	}
 
+	scope, err := convertAccountScope(params.RIAccountScope, "RI")
+	if err != nil {
+		return nil, err
+	}
+
 	input := &costexplorer.GetReservationPurchaseRecommendationInput{
 		Service:              aws.String(getServiceStringForCostExplorer(params.Service)),
 		PaymentOption:        convertPaymentOption(params.PaymentOption),
 		TermInYears:          convertTermInYears(params.Term),
 		LookbackPeriodInDays: convertLookbackPeriod(params.LookbackPeriod),
-		AccountScope:         types.AccountScopeLinked,
+		AccountScope:         scope,
 	}
 
 	if isEC2Service(params.Service) {
diff --git a/providers/aws/recommendations/client_ri_account_scope_test.go b/providers/aws/recommendations/client_ri_account_scope_test.go
new file mode 100644
index 00000000..601e89aa
--- /dev/null
+++ b/providers/aws/recommendations/client_ri_account_scope_test.go
@@ -0,0 +1,61 @@
+package recommendations_test
+
+import (
+	"context"
+	"encoding/json"
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"github.com/aws/aws-sdk-go-v2/aws"
+	"github.com/stretchr/testify/require"
+
+	"github.com/LeanerCloud/cloud-commitments-go/pkg/common"
+	"github.com/LeanerCloud/cloud-commitments-go/providers/aws/recommendations"
+)
+
+type riScopeFixture struct{ scopes []string }
+
+func (f *riScopeFixture) Do(req *http.Request) (*http.Response, error) {
+	var input map[string]any
+	if err := json.NewDecoder(req.Body).Decode(&input); err != nil {
+		return nil, err
+	}
+	scope, _ := input["AccountScope"].(string)
+	f.scopes = append(f.scopes, scope)
+	return &http.Response{StatusCode: http.StatusOK, Header: http.Header{"Content-Type": {"application/x-amz-json-1.1"}},
+		Body: io.NopCloser(strings.NewReader(`{"Recommendations":[]}`)), Request: req}, nil
+}
+
+func riScopeClient(f *riScopeFixture) *recommendations.Client {
+	return recommendations.NewClient(&aws.Config{Region: "us-east-1", HTTPClient: f, RetryMaxAttempts: 1,
+		Credentials: aws.CredentialsProviderFunc(func(context.Context) (aws.Credentials, error) {
+			return aws.Credentials{AccessKeyID: "synthetic", SecretAccessKey: "synthetic"}, nil
+		})})
+}
+
+func TestRIAccountScope(t *testing.T) {
+	t.Parallel()
+	for _, tc := range []struct{ in, want string }{
+		{"", "LINKED"}, {"linked", "LINKED"}, {"payer", "PAYER"}, {"PAYER", "PAYER"},
+	} {
+		t.Run(tc.in, func(t *testing.T) {
+			t.Parallel()
+			f := &riScopeFixture{}
+			_, err := riScopeClient(f).GetRecommendations(context.Background(), &common.RecommendationParams{
+				Service: common.ServiceRDS, Term: "1yr", PaymentOption: "no-upfront", LookbackPeriod: "7d", RIAccountScope: tc.in})
+			require.NoError(t, err)
+			require.Equal(t, []string{tc.want}, f.scopes)
+		})
+	}
+}
+
+func TestRIAccountScopeRejectsUnknown(t *testing.T) {
+	t.Parallel()
+	f := &riScopeFixture{}
+	_, err := riScopeClient(f).GetRecommendations(context.Background(), &common.RecommendationParams{
+		Service: common.ServiceRDS, Term: "1yr", PaymentOption: "no-upfront", LookbackPeriod: "7d", RIAccountScope: "org"})
+	require.ErrorContains(t, err, "invalid RI account scope")
+	require.Empty(t, f.scopes)
+}
diff --git a/providers/aws/recommendations/collection_sp.go b/providers/aws/recommendations/collection_sp.go
index 96ed4b23..e6981b64 100644
--- a/providers/aws/recommendations/collection_sp.go
+++ b/providers/aws/recommendations/collection_sp.go
@@ -62,13 +62,19 @@ func (c *Client) getSavingsPlansRecommendations(ctx context.Context, params *com
 // the Cost Explorer scope. Empty is linked, the long-standing default; an
 // unknown value is an error rather than a silent fallback.
 func convertSavingsPlansAccountScope(s string) (types.AccountScope, error) {
+	return convertAccountScope(s, "Savings Plans")
+}
+
+// convertAccountScope is shared by the Savings Plans and RI recommendation
+// paths so both accept the same values.
+func convertAccountScope(s, kind string) (types.AccountScope, error) {
 	switch strings.ToLower(s) {
 	case "", "linked":
 		return types.AccountScopeLinked, nil
 	case "payer":
 		return types.AccountScopePayer, nil
 	}
-	return "", fmt.Errorf("invalid Savings Plans account scope %q: want linked or payer", s)
+	return "", fmt.Errorf("invalid %s account scope %q: want linked or payer", kind, s)
 }
 
 func (c *Client) fetchSPAllPages(