Articles can only be funded by the publication fund if the total costs do not exceed € 2000 or US$ 2210 respectively, including VAT.
Please be advised that the costs quoted by publishers are usually without VAT (e.g. accompanied by phrases like “excl. taxes”). In these cases, you have to add 19% VAT to the price given. When, for example, the APCs are US$ 1,950, the actual total cost would be US$ 2,320.50 and would therefore be above the maximum amount of US$ 2,210.
In the case of journals that fall under one of the publishing agreements, you can probably deduct the discount before adding taxes. Journals published by Frontiers are an exception here: the APCs will be discounted to stay below the maximum threshold, no matter the asking price.