--- a/net/minecraft/data/TagsProvider.java
+++ b/net/minecraft/data/TagsProvider.java
@@ -28,10 +28,18 @@
    protected final DataGenerator field_200433_a;
    protected final Registry<T> field_200435_c;
    protected final Map<ResourceLocation, ITag.Builder> field_200434_b = Maps.newLinkedHashMap();
+   protected final String modId;
+   protected final net.minecraftforge.common.data.ExistingFileHelper existingFileHelper;
 
+   @Deprecated//Forge, Use ModID version.
    protected TagsProvider(DataGenerator p_i49827_1_, Registry<T> p_i49827_2_) {
+      this(p_i49827_1_, p_i49827_2_, "vanilla", null);
+   }
+   protected TagsProvider(DataGenerator p_i49827_1_, Registry<T> p_i49827_2_, String modId, @javax.annotation.Nullable net.minecraftforge.common.data.ExistingFileHelper existingFileHelper) {
       this.field_200433_a = p_i49827_1_;
       this.field_200435_c = p_i49827_2_;
+      this.modId = modId;
+      this.existingFileHelper = existingFileHelper;
    }
 
    protected abstract void func_200432_c();
@@ -47,12 +55,14 @@
          return this.field_200435_c.func_241873_b(p_240527_1_).orElse((T)null);
       };
       this.field_200434_b.forEach((p_240524_4_, p_240524_5_) -> {
-         List<ITag.Proxy> list = p_240524_5_.func_232963_b_(function, function1).collect(Collectors.toList());
+         // FORGE: Add validation via existing resources
+         List<ITag.Proxy> list = p_240524_5_.func_232963_b_(function, function1).filter(this::missing).collect(Collectors.toList());
          if (!list.isEmpty()) {
             throw new IllegalArgumentException(String.format("Couldn't define tag %s as it is missing following references: %s", p_240524_4_, list.stream().map(Objects::toString).collect(Collectors.joining(","))));
          } else {
             JsonObject jsonobject = p_240524_5_.func_232965_c_();
             Path path = this.func_200431_a(p_240524_4_);
+            if (path == null) return; //Forge: Allow running this data provider without writing it. Recipe provider needs valid tags.
 
             try {
                String s = field_200437_e.toJson((JsonElement)jsonobject);
@@ -74,11 +84,26 @@
       });
    }
 
+   private boolean missing(ITag.Proxy reference) {
+      ITag.ITagEntry entry = reference.func_232968_a_();
+      // We only care about non-optional tag entries, this is the only type that can reference a resource and needs validation
+      // Optional tags should not be validated
+      if (entry instanceof ITag.TagEntry) {
+         return existingFileHelper == null || !existingFileHelper.exists(((ITag.TagEntry)entry).getId(), net.minecraft.resources.ResourcePackType.SERVER_DATA, ".json", "tags/" + getTagFolder());
+      }
+      return false;
+   }
+
+   @SuppressWarnings({ "unchecked", "rawtypes" })
+   protected String getTagFolder() {
+      return ((Registry)Registry.field_212617_f).func_177774_c(field_200435_c).func_110623_a() + "s";
+   }
+
    protected abstract Path func_200431_a(ResourceLocation p_200431_1_);
 
    protected TagsProvider.Builder<T> func_240522_a_(ITag.INamedTag<T> p_240522_1_) {
       ITag.Builder itag$builder = this.func_240525_b_(p_240522_1_);
-      return new TagsProvider.Builder<>(itag$builder, this.field_200435_c, "vanilla");
+      return new TagsProvider.Builder<>(itag$builder, this.field_200435_c, modId);
    }
 
    protected ITag.Builder func_240525_b_(ITag.INamedTag<T> p_240525_1_) {
@@ -87,7 +112,7 @@
       });
    }
 
-   public static class Builder<T> {
+   public static class Builder<T> implements net.minecraftforge.common.extensions.IForgeTagBuilder<T> {
       private final ITag.Builder field_240528_a_;
       private final Registry<T> field_240529_b_;
       private final String field_240530_c_;
@@ -115,5 +140,18 @@
          });
          return this;
       }
+
+      public TagsProvider.Builder<T> add(ITag.ITagEntry tag) {
+          field_240528_a_.func_232955_a_(tag, field_240530_c_);
+          return this;
+      }
+
+      public ITag.Builder getInternalBuilder() {
+          return field_240528_a_;
+      }
+
+      public String getModID() {
+          return field_240530_c_;
+      }
    }
 }