diff --git a/src/main/java/org/prebid/server/bidder/dmx/DmxBidder.java b/src/main/java/org/prebid/server/bidder/dmx/DmxBidder.java
index dad5b15c175..28b345c5069 100644
--- a/src/main/java/org/prebid/server/bidder/dmx/DmxBidder.java
+++ b/src/main/java/org/prebid/server/bidder/dmx/DmxBidder.java
@@ -156,20 +156,16 @@ private static Imp fetchParams(Imp imp, ExtImpDmx extImp) {
 
         final String tagId = extImp.getTagId();
         if (StringUtils.isNotBlank(tagId)) {
-            updatedImp = Imp.builder()
-                    .id(imp.getId())
+            updatedImp = imp.toBuilder()
                     .tagid(tagId)
-                    .ext(imp.getExt())
                     .secure(SECURE)
                     .build();
         }
 
         final String dmxId = extImp.getDmxId();
         if (StringUtils.isNotBlank(dmxId)) {
-            updatedImp = Imp.builder()
-                    .id(imp.getId())
+            updatedImp = imp.toBuilder()
                     .tagid(dmxId)
-                    .ext(imp.getExt())
                     .secure(SECURE)
                     .build();
         }
diff --git a/src/main/java/org/prebid/server/proto/openrtb/ext/request/dmx/ExtImpDmx.java b/src/main/java/org/prebid/server/proto/openrtb/ext/request/dmx/ExtImpDmx.java
index f056c075814..aadd640dea1 100644
--- a/src/main/java/org/prebid/server/proto/openrtb/ext/request/dmx/ExtImpDmx.java
+++ b/src/main/java/org/prebid/server/proto/openrtb/ext/request/dmx/ExtImpDmx.java
@@ -20,9 +20,7 @@ public class ExtImpDmx {
     @JsonProperty("memberid")
     String memberId;
 
-    @JsonProperty("publisher_id")
     String publisherId;
 
-    @JsonProperty("seller_id")
     String sellerId;
 }
diff --git a/src/test/java/org/prebid/server/bidder/dmx/DmxBidderTest.java b/src/test/java/org/prebid/server/bidder/dmx/DmxBidderTest.java
index 663d5ce69e3..b11e21a00ee 100644
--- a/src/test/java/org/prebid/server/bidder/dmx/DmxBidderTest.java
+++ b/src/test/java/org/prebid/server/bidder/dmx/DmxBidderTest.java
@@ -1,7 +1,6 @@
 package org.prebid.server.bidder.dmx;
 
 import com.fasterxml.jackson.core.JsonProcessingException;
-import com.fasterxml.jackson.databind.JsonNode;
 import com.iab.openrtb.request.Banner;
 import com.iab.openrtb.request.BidRequest;
 import com.iab.openrtb.request.Format;
@@ -24,6 +23,7 @@
 import org.prebid.server.proto.openrtb.ext.request.dmx.ExtImpDmx;
 import org.prebid.server.proto.openrtb.ext.response.BidType;
 
+import java.math.BigDecimal;
 import java.util.List;
 import java.util.function.Function;
 
@@ -32,7 +32,6 @@
 import static java.util.function.Function.identity;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
-import static org.assertj.core.api.Assertions.tuple;
 import static org.prebid.server.proto.openrtb.ext.response.BidType.banner;
 import static org.prebid.server.proto.openrtb.ext.response.BidType.video;
 
@@ -96,22 +95,58 @@ public void makeHttpRequestsShouldReturnErrorIfUserIdIsEmpty() {
     @Test
     public void makeHttpRequestsShouldModifyImpIfBannerFormatIsNotEmpty() {
         // given
+        final Imp givenImp = Imp.builder()
+                .id("id")
+                .bidfloor(BigDecimal.ONE)
+                .banner(Banner.builder()
+                        .format(singletonList(Format.builder().w(300).h(500).build()))
+                        .build())
+                .ext(mapper.valueToTree(ExtPrebid.of(null,
+                        ExtImpDmx.builder()
+                                .tagId("tagId")
+                                .dmxId("dmxId")
+                                .memberId("memberId")
+                                .publisherId("publisherId")
+                                .sellerId("sellerId")
+                                .build())))
+                .build();
         final BidRequest bidRequest = BidRequest.builder()
-                .imp(singletonList(
-                        Imp.builder()
-                                .id("id")
-                                .banner(Banner.builder()
-                                        .format(singletonList(Format.builder().w(300).h(500).build()))
-                                        .build())
-                                .ext(mapper.valueToTree(ExtPrebid.of(null,
-                                        ExtImpDmx.builder()
-                                                .tagId("tagId")
-                                                .dmxId("dmxId")
-                                                .memberId("memberId")
-                                                .publisherId("publisherId")
-                                                .sellerId("sellerId")
-                                                .build())))
-                                .build()))
+                .imp(singletonList(givenImp))
+                .user(User.builder().id("userId").build())
+                .build();
+
+        // when
+        final Result<List<HttpRequest<BidRequest>>> result = dmxBidder.makeHttpRequests(bidRequest);
+
+        // then
+        final Imp expectedImp = givenImp.toBuilder()
+                .tagid("dmxId")
+                .secure(1)
+                .build();
+        assertThat(result.getErrors()).isEmpty();
+        assertThat(result.getValue()).hasSize(1)
+                .extracting(httpRequest -> mapper.readValue(httpRequest.getBody(), BidRequest.class))
+                .flatExtracting(BidRequest::getImp)
+                .containsExactly(expectedImp);
+    }
+
+    @Test
+    public void makeHttpRequestsShouldWriteTagIdToImpIfItIsPresentAndDmxIsMissing() {
+        // given
+        final Imp givenImp = Imp.builder()
+                .banner(Banner.builder()
+                        .format(singletonList(Format.builder().build()))
+                        .build())
+                .ext(mapper.valueToTree(ExtPrebid.of(null,
+                        ExtImpDmx.builder()
+                                .tagId("tagId")
+                                .dmxId("")
+                                .memberId("memberId")
+                                .publisherId("publisherId")
+                                .build())))
+                .build();
+        final BidRequest bidRequest = BidRequest.builder()
+                .imp(singletonList(givenImp))
                 .user(User.builder().id("userId").build())
                 .build();
 
@@ -120,19 +155,11 @@ public void makeHttpRequestsShouldModifyImpIfBannerFormatIsNotEmpty() {
 
         // then
         assertThat(result.getErrors()).isEmpty();
-        final JsonNode expectedImpExt = mapper.valueToTree(ExtPrebid.of(null,
-                ExtImpDmx.builder()
-                        .tagId("tagId")
-                        .dmxId("dmxId")
-                        .memberId("memberId")
-                        .publisherId("publisherId")
-                        .sellerId("sellerId")
-                        .build()));
         assertThat(result.getValue()).hasSize(1)
                 .extracting(httpRequest -> mapper.readValue(httpRequest.getBody(), BidRequest.class))
                 .flatExtracting(BidRequest::getImp)
-                .extracting(Imp::getId, Imp::getTagid, Imp::getExt, Imp::getSecure)
-                .containsOnly(tuple("id", "dmxId", expectedImpExt, 1));
+                .extracting(Imp::getTagid)
+                .containsExactly("tagId");
     }
 
     @Test