diff --git a/CarpetX/src/interpolate.cxx b/CarpetX/src/interpolate.cxx
index eee39a9a8..40ec7779c 100644
--- a/CarpetX/src/interpolate.cxx
+++ b/CarpetX/src/interpolate.cxx
@@ -664,6 +664,9 @@ extern "C" void CarpetX_Interpolate(const CCTK_POINTER_TO_CONST cctkGH_,
     givis.at(v) = {gi, vi};
   }
 
+  rat64 min_level_iteration_used = -1;
+  rat64 max_level_iteration_used = -1;
+  bool requires_interpolation_in_time = false;
   for (const auto &patchdata : ghext->patchdata) {
     const int patch = patchdata.patch;
     for (const auto &leveldata : patchdata.leveldata) {
@@ -676,6 +679,15 @@ extern "C" void CarpetX_Interpolate(const CCTK_POINTER_TO_CONST cctkGH_,
         const GridDesc grid(leveldata, mfp);
         // const int component = mfp.index();
 
+        min_level_iteration_used =
+            min_level_iteration_used != -1
+                ? std::min(min_level_iteration_used, leveldata.iteration)
+                : leveldata.iteration;
+        max_level_iteration_used =
+            max_level_iteration_used != -1
+                ? std::max(max_level_iteration_used, leveldata.iteration)
+                : leveldata.iteration;
+
         const int np = pti.numParticles();
         const auto &particles = pti.GetArrayOfStructs();
 
@@ -823,8 +835,32 @@ extern "C" void CarpetX_Interpolate(const CCTK_POINTER_TO_CONST cctkGH_,
     }
   }
 
-  // Collect particles back
   const MPI_Comm comm = amrex::ParallelDescriptor::Communicator();
+
+  // check if interpolation in time (unsupported) would be needed
+  if (use_subcycling) {
+    const double local_iteration_used[2] = {
+        min_level_iteration_used != -1
+            ? -double(min_level_iteration_used)
+            : -std::numeric_limits<double>::infinity(),
+        max_level_iteration_used != -1
+            ? +double(max_level_iteration_used)
+            : -std::numeric_limits<double>::infinity()};
+    double global_iteration_used[2] = {0.};
+    MPI_Allreduce(local_iteration_used, global_iteration_used, 2, MPI_DOUBLE,
+                  MPI_MAX, comm);
+    const double min_iteration_used = -global_iteration_used[0];
+    const double max_iteration_used = +global_iteration_used[1];
+    // Did two (or one) ranks use different iterations?
+    if (max_iteration_used != min_iteration_used) {
+      CCTK_VERROR("Interpolation in time required when interpolating %s at "
+                  "iteration %d",
+                  nvars > 0 ? CCTK_FullVarName(varinds[0]) : "no variable",
+                  cctkGH->cctk_iteration);
+    }
+  }
+
+  // Collect particles back
   const MPI_Datatype datatype = mpi_datatype<CCTK_REAL>::value;
 
   std::vector<int> sendcounts(nprocs);
diff --git a/CarpetX/src/io.cxx b/CarpetX/src/io.cxx
index e6fdff93a..1a920c05d 100644
--- a/CarpetX/src/io.cxx
+++ b/CarpetX/src/io.cxx
@@ -609,6 +609,24 @@ void Checkpoint(const cGH *const restrict cctkGH) {
     return;
   }
 
+  if (use_subcycling) { // currently checkpoint and recovery only works if all
+                        // levels are aligned in time
+    rat64 level_iteration = -1;
+    for (const auto &patchdata : ghext->patchdata) {
+      for (const auto &leveldata : patchdata.leveldata) {
+        if (level_iteration == -1) {
+          level_iteration = leveldata.iteration;
+        } else {
+          if (leveldata.iteration != level_iteration) {
+            CCTK_VERROR("Checkpointing is only allowed if all levels are "
+                        "aligned in time, not at %d",
+                        cctkGH->cctk_iteration);
+          }
+        }
+      }
+    }
+  }
+
   if (cctkGH->cctk_iteration <= last_checkpoint_iteration) {
     CCTK_VINFO(
         "Already wrote checkpoint at iteration %d; skipping checkpointing",