The tastyworks platform defaults outright futures contracts to the active month. When you type in the futures contract symbol, such as /ES, then the platform will quote the active month, allowing you to line up trades quickly. To trade or look up a quote of a back month contract (further in time), type the month and year code.
For example, if the active month for /ES is /ESZ8 (E-mini S&P future-Dec. 2018), but you want to trade June 2019 contract, then you need to enter /ESM9 instead.
To view a list of available future contracts and a guide to month codes, then please click here.