getLayout()->createBlock('Magento\Customer\Block\Widget\Dob') ->setDate($block->getCustomer()->getDob()) ->toHtml() ?> For checkout/onepage/billing.phtml: = $block->getLayout()->createBlock('Magento\Customer\Block\Widget\Dob') ->setDate($block->getCustomer()->getDob()) ->setFieldIdFormat('billing:%s') ->setFieldNameFormat('billing[%s]') ->toHtml() ?> NOTE: Regarding styles - if we leave it this way, we'll move it to boxes.css. Alternatively we could calculate widths automatically using block input parameters. */ $fieldCssClass = 'field date field-' . $block->getHtmlId(); $fieldCssClass .= $block->isRequired() ? ' required' : ''; ?>