I'll get back to you on that.

Meaning

I will respond to your question or request later.

Examples

• John: 'What are the next steps?'
• Alice: '<b>I'll get back to you on that</b> after I've reviewed the data.'
• John: '<b>I'll get back to you on that</b>; I'm still analyzing the data.'
• Alice: 'Have you finished the report?'