Should I use present or past tense to refer to job activities on my CV?

Some employers prefer current tense while others refer to all duties and activities in the past tense. As a rule of thumb, you should not mix the tenses. It is easier to refer to all duties and activities in the past tense on your CV. If you find that you have to make a distinction to avoid confusion, you can indicate activities that you are still doing as 'current'.