The pricing policy app allows you to define the discount that should be applied to a variant, based on its collection, price, stock levels and age.

You can define multiple sets of rules, which can be active for different time periods, allowing you to set the price for sales and holiday periods.

Prices

All prices are set as a discount compared to the 'Compare At' price. If a 'Compare At' price is not set, one will be added to the variant set to the current price. 

If you store already has prices that have discounts pre-applied, then be careful setting up the rules, as it may increase the prices. For example if the prices are already 20% discounted, and you set a discount of 10%, then the price may increase by 10%.

Make sure you run a test before enabling any new changes, to prevent any unwanted changes.

Excluding Products
If the 'Compare At' price is set to $0.00 the job will not be run, this can be used to your advantage if you don't want prices changed on certain items.

Each rule is run in the order they are presented, from top to bottom. Likewise for groups of rules.

The 'Increase Only' and 'Decrease Only' rules mean that they will only activate if the price is higher or lower than the product price. This means, for example, you can chain 'Only Decrease' rules together and it will choose the lowest price of all of those rules.

The 'Set to Percentage' rule will always run, and if it is the last rule then that rule will overrule the previous ones and set the product to have that percentage discount.

The keep same rule works almost like the opposite - it means to keep the price as it currently is regardless of previous rules. It is usually used when you are applying a discount to your entire store, but want to keep one collection of items at full price (say new-in-stock).

Products can be tagged if they match a rule.

Each product in a group will only be tagged once by the last matching rule.

If you want to tag a single product multiple times you need to create a new group.

You may need to ensure that your products can only be tagged when they match a rule, but also untagged when they are no longer a match.

For example you may have a rule that says tag everything in the 20% Off collection with the tag sale-20. Once the product is no longer in the 20% Off collection the tag will not be automatically removed. To fix this issue you should create a rule at the top of the group for all products (you may want to create a collection called all, with all products in it). Set the tag to empty for this rule. Now when the rule is run all products that no longer match any lower rules will have the tag removed, so in this case the tag sale-20 will be removed.

Values can be rounded to a number of close values, such a 5c, 50c, $1 or $10 (or the currency of your store). Simply select the rounding option when creating a rule.

Can also choose to subract a value after rounding. This can work well if you want to give your prices a perceived lower number, such as $19.99 instead of $20.00.

An additional criteria that can be added to a rule is the variant age. This enables you to create rules for discounting older products, or offering promotional sale prices for new items.

Simply select the product age in days and any products over that age will match the rule.

If you have a group of products that you want to set the same specific price for all of them there is a trick you can use.

Set the discount to 100%, then in the 'Subtract value after rounding' enter the negative of the fixed price. So for example a fixed price of $20.45, would have a value of -20.45 in that field.

There is a test feature that allows you to test how your store will be changed from how it is currently and also to how it might change on a given day.

This allows you to see what your store might look like once all the rules have been run on that day. It will not make any changes to your store, and the test results will be emailed to you.

When you make a change the Pricing Policy will be disabled until you click the Enable & Run button.

This is to prevent the pricing policy from running before you have had a chance to check the results, and also so it doesn't run while you are in the middle of making changes.

Your store will be updated when the next store wide update job is run. This is usually every hour or two for small and medium stores.

If you have a large store you may find that the start date will only be accurate to your update frequency. You can always manually run an update by pressing Run.

Another point to note is that if your store has a very large number products then it may take a while to run. Shopify places a limit on the number of updates that can be made to a store.

A rule of thumb is that only 80-100 products can be updated per minute. If you have 10,000 products you should expect at least a two hour update time.

All dates and times are measured in UTC time, so please adjust for your local time zone accordingly (UK/Europe 0 or +2 hours, Australia +8 to +11 hours, North America -5 to -8 hours). A good free converter can be found at http://www.worldtimebuddy.com/utc-to-est-converter

The pricing policy app does not revert prices back automatically, you'll need to set up an 'everyday price' policy in order to revert prices.

To do this, you'll need to create a new policy, and make sure it is at the top of the list always, you'll need to set the expiry date to very far in the future. And set it up to apply a discount of 0% to all products (or the collection of your choice).

Here's how it should look in the app :

and when setting up the rules: