diff --git a/src/main/scala/com/fulcrumgenomics/bam/api/SamRecord.scala b/src/main/scala/com/fulcrumgenomics/bam/api/SamRecord.scala
index 9ca28fd51..fb33e7c89 100644
--- a/src/main/scala/com/fulcrumgenomics/bam/api/SamRecord.scala
+++ b/src/main/scala/com/fulcrumgenomics/bam/api/SamRecord.scala
@@ -30,6 +30,7 @@ import com.fulcrumgenomics.alignment.Cigar
 import htsjdk.samtools
 import htsjdk.samtools.SamPairUtil.PairOrientation
 import htsjdk.samtools._
+import htsjdk.samtools.util.CoordMath
 
 // TODO long-term: methods for 5'end, 3' end, unclipped 5' end and unclipped 3' end
 // TODO long-term: replacement for alignment blocks?
@@ -169,11 +170,15 @@ trait SamRecord {
 
   @inline final def mateStart: Int = getMateAlignmentStart
   @inline final def mateStart_=(s: Int):Unit = setMateAlignmentStart(s)
+
+  @inline final def mateCigar: Option[Cigar] = {
+    require(paired && mateMapped, "Cannot get a mate cigar on read without a mapped mate.")
+    get[String]("MC").map(Cigar.apply)
+  }
   @inline final def mateEnd: Option[Int] = {
     require(paired && mateMapped, "Cannot get mate end position on read without a mapped mate.")
     get[String]("MC").map(cig => mateStart + Cigar(cig).lengthOnTarget - 1)
   }
-
   @inline final def mateUnclippedStart: Option[Int] = {
     require(paired && mateMapped, "Cannot get mate unclipped start position on read without a mapped mate.")
     get[String]("MC").map(cig => mateStart - Cigar(cig).iterator.takeWhile(_.operator.isClipping).map(_.length).sum)
@@ -185,6 +190,13 @@ trait SamRecord {
       mateStart + cigar.lengthOnTarget - 1 + cigar.reverseIterator.takeWhile(_.operator.isClipping).map(_.length).sum
     }
   }
+  @inline final def matesOverlap: Option[Boolean] = {
+    require(mapped && paired && mateMapped, "Cannot determine if mates overlap without paired mates that are both mapped.")
+    if (refIndex != mateRefIndex) Some(false)
+    else if (mateStart > end) Some(false)
+    else if (mateStart >= start && mateStart <= end) Some(true)
+    else mateEnd.map(mateEnd => CoordMath.overlaps(start, end, mateStart, mateEnd))
+  }
 
   @inline final def insertSize: Int = getInferredInsertSize
   @inline final def insertSize_=(s: Int):Unit = setInferredInsertSize(s)
diff --git a/src/main/scala/com/fulcrumgenomics/rnaseq/EstimateRnaSeqInsertSize.scala b/src/main/scala/com/fulcrumgenomics/rnaseq/EstimateRnaSeqInsertSize.scala
index 3e5847a62..e8fd47249 100644
--- a/src/main/scala/com/fulcrumgenomics/rnaseq/EstimateRnaSeqInsertSize.scala
+++ b/src/main/scala/com/fulcrumgenomics/rnaseq/EstimateRnaSeqInsertSize.scala
@@ -206,9 +206,8 @@ object EstimateRnaSeqInsertSize {
   private def DifferentReferenceIndexFilter                = filter(r => r.refIndex != r.mateRefIndex)
 
   private[rnaseq] def getAndRequireMateCigar(rec: SamRecord): Cigar = {
-    rec.get[String](SAMTag.MC.name()) match {
-      case None => throw new IllegalStateException(s"Mate CIGAR (Tag MC) not found for $rec, consider using SetMateInformation.")
-      case Some(mc) => Cigar(mc)
+    rec.mateCigar.getOrElse {
+      throw new IllegalStateException(s"Mate CIGAR (Tag 'MC') not found for $rec, consider using SetMateInformation.")
     }
   }
 
diff --git a/src/test/scala/com/fulcrumgenomics/bam/api/SamRecordTest.scala b/src/test/scala/com/fulcrumgenomics/bam/api/SamRecordTest.scala
index 7069f27bc..38251e0c4 100644
--- a/src/test/scala/com/fulcrumgenomics/bam/api/SamRecordTest.scala
+++ b/src/test/scala/com/fulcrumgenomics/bam/api/SamRecordTest.scala
@@ -27,7 +27,7 @@ package com.fulcrumgenomics.bam.api
 import com.fulcrumgenomics.alignment.Cigar
 import com.fulcrumgenomics.testing.SamBuilder.{Minus, Plus}
 import com.fulcrumgenomics.testing.{SamBuilder, UnitSpec}
-import htsjdk.samtools.{SAMTag, TextCigarCodec}
+import htsjdk.samtools.TextCigarCodec
 import org.scalatest.OptionValues
 
 class SamRecordTest extends UnitSpec with OptionValues {
@@ -186,12 +186,41 @@ class SamRecordTest extends UnitSpec with OptionValues {
     rec.basesString should not be clone.basesString
   }
 
+  "SamRecord.mateCigar" should "raise an exception for a fragment without a mate" in {
+    val Some(rec) = new SamBuilder(readLength = 100).addFrag(start = 1, cigar = "100M")
+    an[IllegalArgumentException] shouldBe thrownBy { rec.mateCigar }
+  }
+
+  it should "raise an exception for a paired read if the mate is unmapped" in {
+    val Seq(rec1, _): Seq[SamRecord] = new SamBuilder(readLength = 100).addPair(start1 = 1, unmapped2 = true)
+    an[IllegalArgumentException] shouldBe thrownBy { rec1.mateCigar }
+  }
+
+  it should "return None for a paired read without the 'MC' tag set" in {
+    val Seq(rec1, rec2): Seq[SamRecord] = new SamBuilder(readLength = 100).addPair(start1 = 1, start2 = 200)
+    rec1.remove("MC")
+    rec2.remove("MC")
+    rec1.mateCigar shouldBe None
+    rec2.mateCigar shouldBe None
+  }
+
+  it should "return the mates cigar for a paired read with the 'MC' tag set" in {
+    val Seq(rec1, rec2): Seq[SamRecord] = new SamBuilder(readLength = 100).addPair(
+      start1 = 1,
+      start2 = 200,
+      cigar1 = "50M1I49M",
+      cigar2 = "49M1I50M"
+    )
+    rec1.mateCigar.value shouldBe Cigar("49M1I50M")
+    rec2.mateCigar.value shouldBe Cigar("50M1I49M")
+  }
+
   "SamRecord.mateUnclippedStart/End" should "return None if no mate cigar set" in {
     val builder = new SamBuilder(readLength=50)
     val recs = builder.addPair(start1=10, start2=50)
 
     recs.foreach { r =>
-      r(SAMTag.MC.name) = null // Clear mate cigar
+      r("MC") = null // Clear mate cigar
       r.mateUnclippedStart.isEmpty shouldBe true
       r.mateUnclippedEnd.isEmpty shouldBe true
     }
@@ -221,4 +250,43 @@ class SamRecordTest extends UnitSpec with OptionValues {
     r2.unclippedEnd shouldBe 94
     r1.mateUnclippedEnd.value shouldBe r2.unclippedEnd
   }
+
+  "SamRecord.matesOverlap" should "raise exceptions if any pre-requisite check isn't true" in {
+    an[IllegalArgumentException] shouldBe thrownBy { new SamBuilder(readLength = 100).addFrag(start = 1).value.matesOverlap }
+    an[IllegalArgumentException] shouldBe thrownBy { new SamBuilder(readLength = 100).addPair(start1 = 1, unmapped2 = true).foreach(_.matesOverlap) }
+    an[IllegalArgumentException] shouldBe thrownBy { new SamBuilder(readLength = 100).addPair(start2 = 1, unmapped1 = true).foreach(_.matesOverlap) }
+  }
+
+  it should "return false when both reads in a pair are mapped but to different contigs" in {
+    new SamBuilder(readLength = 100).addPair(start1 = 1, start2 = 1, contig = 0, contig2 = Some(1))
+      .foreach(_.matesOverlap.value shouldBe false)
+  }
+
+  it should "return false when both reads in a pair are mapped to the same contig but do not overlap" in {
+    new SamBuilder(readLength = 100).addPair(start1 = 1, start2 = 101, contig = 0, contig2 = Some(0))
+      .foreach(_.matesOverlap.value shouldBe false)
+  }
+
+  it should "return true when reads overlap by one base pair in FR orientation" in {
+    new SamBuilder(readLength = 100).addPair(start1 = 1, start2 = 100, contig = 0, contig2 = Some(0))
+      .foreach(_.matesOverlap.value shouldBe true)
+  }
+
+  it should "return true when reads overlap by one base pair in RF orientation" in {
+    new SamBuilder(readLength = 100).addPair(start1 = 100, start2 = 1, contig = 0, contig2 = Some(0))
+      .foreach(_.matesOverlap.value shouldBe true)
+  }
+
+  it should "return true when reads overlap completely" in {
+    new SamBuilder(readLength = 100).addPair(start1 = 1, start2 = 1, contig = 0, contig2 = Some(0))
+      .foreach(_.matesOverlap.value shouldBe true)
+  }
+
+  it should "return true when mates overlap and we know the start of the mate, and None for when we don't know the end of the mate" in {
+    val List(rec1, rec2) = new SamBuilder(readLength = 100).addPair(start1 = 10, start2 = 1, contig = 0, contig2 = Some(0))
+    rec1.remove("MC")
+    rec2.remove("MC")
+    rec1.matesOverlap shouldBe None // Mate's start is not enclosed by rec, and mate's end cannot be determined
+    rec2.matesOverlap.value shouldBe true // Mate's start is enclosed by rec, regardless of where mate end is
+  }
 }