diff --git a/packages/kbn-esql-validation-autocomplete/src/autocomplete/autocomplete.test.ts b/packages/kbn-esql-validation-autocomplete/src/autocomplete/autocomplete.test.ts
index 8524cd4950955..e463902554074 100644
--- a/packages/kbn-esql-validation-autocomplete/src/autocomplete/autocomplete.test.ts
+++ b/packages/kbn-esql-validation-autocomplete/src/autocomplete/autocomplete.test.ts
@@ -1262,41 +1262,33 @@ describe('autocomplete', () => {
   describe('Replacement ranges are attached when needed', () => {
     testSuggestions('FROM a | WHERE doubleField IS NOT N/', [
       { text: 'IS NOT NULL', rangeToReplace: { start: 28, end: 35 } },
-      { text: 'IS NULL', rangeToReplace: { start: 35, end: 35 } },
+      { text: 'IS NULL', rangeToReplace: { start: 36, end: 36 } },
       '!= $0',
-      '< $0',
-      '<= $0',
       '== $0',
-      '> $0',
-      '>= $0',
       'IN $0',
+      'AND $0',
+      'NOT',
+      'OR $0',
     ]);
     testSuggestions('FROM a | WHERE doubleField IS N/', [
       { text: 'IS NOT NULL', rangeToReplace: { start: 28, end: 31 } },
       { text: 'IS NULL', rangeToReplace: { start: 28, end: 31 } },
-      { text: '!= $0', rangeToReplace: { start: 31, end: 31 } },
-      '< $0',
-      '<= $0',
+      { text: '!= $0', rangeToReplace: { start: 32, end: 32 } },
       '== $0',
-      '> $0',
-      '>= $0',
       'IN $0',
+      'AND $0',
+      'NOT',
+      'OR $0',
     ]);
     testSuggestions('FROM a | EVAL doubleField IS NOT N/', [
       { text: 'IS NOT NULL', rangeToReplace: { start: 27, end: 34 } },
       'IS NULL',
-      '% $0',
-      '* $0',
-      '+ $0',
-      '- $0',
-      '/ $0',
       '!= $0',
-      '< $0',
-      '<= $0',
       '== $0',
-      '> $0',
-      '>= $0',
       'IN $0',
+      'AND $0',
+      'NOT',
+      'OR $0',
     ]);
     describe('dot-separated field names', () => {
       testSuggestions(
diff --git a/packages/kbn-esql-validation-autocomplete/src/autocomplete/autocomplete.ts b/packages/kbn-esql-validation-autocomplete/src/autocomplete/autocomplete.ts
index 5d885379f1a94..cf41fd2506c72 100644
--- a/packages/kbn-esql-validation-autocomplete/src/autocomplete/autocomplete.ts
+++ b/packages/kbn-esql-validation-autocomplete/src/autocomplete/autocomplete.ts
@@ -324,10 +324,16 @@ function findNewVariable(variables: Map<string, ESQLVariable[]>) {
 function workoutBuiltinOptions(
   nodeArg: ESQLAstItem,
   references: Pick<ReferenceMaps, 'fields' | 'variables'>
-): { skipAssign: boolean } {
+): { skipAssign: boolean; commandsToInclude?: string[] } {
+  const commandsToInclude =
+    (isSingleItem(nodeArg) && nodeArg.text?.toLowerCase().trim().endsWith('null')) ?? false
+      ? ['and', 'or']
+      : undefined;
+
   // skip assign operator if it's a function or an existing field to avoid promoting shadowing
   return {
     skipAssign: Boolean(!isColumnItem(nodeArg) || getColumnForASTNode(nodeArg, references)),
+    commandsToInclude,
   };
 }
 
@@ -447,7 +453,10 @@ function isFunctionArgComplete(
   }
   const hasCorrectTypes = fnDefinition.signatures.some((def) => {
     return arg.args.every((a, index) => {
-      return def.params[index].type === extractTypeFromASTArg(a, references);
+      return (
+        (fnDefinition.name.endsWith('null') && def.params[index].type === 'any') ||
+        def.params[index].type === extractTypeFromASTArg(a, references)
+      );
     });
   });
   if (!hasCorrectTypes) {
@@ -1140,11 +1149,12 @@ async function getBuiltinFunctionNextArgument(
   }
   return suggestions.map<SuggestionRawDefinition>((s) => {
     const overlap = getOverlapRange(queryText, s.text);
+    const offset = overlap.start === overlap.end ? 1 : 0;
     return {
       ...s,
       rangeToReplace: {
-        start: overlap.start,
-        end: overlap.end,
+        start: overlap.start + offset,
+        end: overlap.end + offset,
       },
     };
   });
diff --git a/packages/kbn-esql-validation-autocomplete/src/autocomplete/complete_items.ts b/packages/kbn-esql-validation-autocomplete/src/autocomplete/complete_items.ts
index 42bb02058023b..8d598eb5f2f11 100644
--- a/packages/kbn-esql-validation-autocomplete/src/autocomplete/complete_items.ts
+++ b/packages/kbn-esql-validation-autocomplete/src/autocomplete/complete_items.ts
@@ -59,10 +59,11 @@ export const getBuiltinCompatibleFunctionDefinition = (
   option: string | undefined,
   argType: FunctionParameterType,
   returnTypes?: FunctionReturnType[],
-  { skipAssign }: { skipAssign?: boolean } = {}
+  { skipAssign, commandsToInclude }: { skipAssign?: boolean; commandsToInclude?: string[] } = {}
 ): SuggestionRawDefinition[] => {
   const compatibleFunctions = [...builtinFunctions, ...getTestFunctions()].filter(
     ({ name, supportedCommands, supportedOptions, signatures, ignoreAsSuggestion }) =>
+      (command === 'where' && commandsToInclude ? commandsToInclude.indexOf(name) > -1 : true) &&
       !ignoreAsSuggestion &&
       !/not_/.test(name) &&
       (!skipAssign || name !== '=') &&